Troubleshooting Node Monitoring and Alerts

E2E Networks pre-configures monitoring for default node images. Monitoring data should appear in the Node Details page within 5–10 minutes of launch. Alerts are created and managed from the node Alerts tab or the global alert flow. This guide covers what to do when graphs are missing, alert notifications are not sent, or the Zabbix agent - which collects the data - is not running.

Common Issues

Issue	What to check
Memory or storage chart is missing on the details page	Confirm the node is Running, then select Test Monitoring Service. If the test fails, follow the troubleshooting link in the agent warning.
Test Monitoring Service is disabled	The node is Powered off. Start the node and retry.
Create Alert is disabled	The node is not Running, or the node is a Disaster Recovery target. Start the node, or manage alerts on the source node for DR targets.
Volume Read Ops or Volume Write Ops is not shown	These triggers require a specific volume. From the global Manage Alerts flow they are hidden when multiple nodes or All nodes are selected.
Attached volume monitoring shows "not enabled"	For Linux nodes, run the portal-provided command inside the node and wait 10 to 15 minutes. Windows nodes are handled automatically.
Webcheck create is rejected	A Webcheck with the same URL and required text already exists for the host, or the host has reached its Webcheck limit.
Alert exists but notifications are not received	Check the linked alert group members and confirm the alert is not paused. For notification channel setup, see Node Monitoring.
Agent warning shown after a recent change	Wait a few minutes after node creation, reinstall, or restart. For custom images or modified firewalls, see Node Monitoring.

Details

Memory or Storage Chart is Missing

Charts depend on the Zabbix agent inside the node reporting back to the E2E monitoring server. If a chart is missing on the Node Details page:

Confirm the node is Running. Stopped nodes do not report.
Click Test Monitoring Service on the node details page. The test exercises the round-trip between the portal and the agent.
If the test fails, follow the troubleshooting link inside the agent warning - it points to the right next step based on which check failed.

Test Monitoring Service is Disabled

The Test Monitoring Service action is only available on Running nodes. If it is greyed out, the node is Powered off. Start the node and retry.

Create Alert is Disabled

Two cases hide the Create Alert button:

The node is not Running. Start the node and retry.
The node is a Disaster Recovery target. Alerts are managed on the source node, not on the DR target. Open the source node's Alerts tab to manage triggers.

Volume Read Ops or Volume Write Ops Trigger is Missing

Volume Read Ops and Volume Write Ops are per-volume triggers - they need a specific volume to attach to. From the global Manage Alerts flow, when you select multiple nodes or All nodes, the portal hides these per-volume triggers because there is no single volume to bind to. To create a Volume Ops alert:

Open the node's Alerts tab directly, or
Select a single node in the global flow so the available volumes can be enumerated.

Attached Volume Monitoring Shows "Not Enabled"

When a Block Storage volume is attached to a node, the portal needs to enable monitoring on the new volume:

On Linux nodes, the portal will display a one-line command to run inside the node. Run that command, then wait 10 to 15 minutes for the first data points to appear.
On Windows nodes, this is handled automatically - no command needs to be run.

Webcheck Create is Rejected

The two reasons a Webcheck create can be rejected:

A Webcheck with the same URL and required text already exists for the host. Webchecks are de-duplicated per host.
The host has reached its Webcheck limit of 5 URLs. Delete an unused Webcheck and retry.

Alert Exists but Notifications are Not Received

If an alert is firing in the portal but emails are not arriving:

Check the linked alert group members. An alert is linked to a User Group; if the group is empty or has the wrong addresses, no one receives mail.
Confirm the alert is not paused. Paused alerts continue to be visible but do not send notifications. Resume the alert from the Actions column.

For setting up notification channels, see Node Monitoring.

Agent Warning Shown After a Recent Change

The Zabbix agent takes a few minutes to start reporting after the node has been created, reinstalled, or restarted. Wait a few minutes before assuming the agent is broken.

If the warning persists - typically because you imported a custom image, modified the OS firewall, or removed the Zabbix agent - re-install or reconfigure the agent. See the section below.

Zabbix Agent Troubleshooting

The Zabbix agent runs inside the node and reports metrics to the E2E monitoring service. Default E2E images ship with it pre-installed. If monitoring shows "Cannot connect with agent. TCP connection with VM is failed", or charts are missing, follow the steps below.

Common Causes

Security Group does not allow inbound TCP on port 10050
Zabbix Agent service is not running
Zabbix Agent is not installed
Agent configured with incorrect monitoring server IP
Hostname mismatch in agent configuration
OS-level firewall blocking port 10050
Zabbix Agent process crashed
Incorrect Zabbix Agent version installed

Step 1: Verify Node Security Group Rules

Port 10050 must be open in the node's Security Group before any OS-level configuration matters.

Log in to the E2E MyAccount Portal.
Go to Compute → Nodes and open the node's details page.
Click the Security Group tab.
Verify there is an inbound rule for Custom TCP port 10050 from Any Network.

If the rule is missing, add it:

Type	Protocol	Port Range	Source
Custom TCP	TCP	10050	Any Network (0.0.0.0/0)

important

Opening port 10050 at the OS firewall level alone is not sufficient. The Security Group rule must also permit the traffic.

Step 2: Verify Zabbix Agent Service (Linux)

Check whether the agent service is active:

systemctl status zabbix-agent

On older images without systemd:

service zabbix-agent status

If the agent is stopped, start it and enable it to start on boot:

systemctl start zabbix-agent
systemctl enable zabbix-agent

Step 3: Verify Zabbix Agent Installation

Confirm the Zabbix Agent package is installed.

Ubuntu / Debian:

dpkg -l | grep zabbix

Rocky Linux / AlmaLinux / RHEL:

rpm -qa | grep zabbix

If the package is missing, see Reinstalling the Zabbix Agent.

Step 4: Verify Agent Configuration

Check the configured monitoring servers:

grep ^Server= /etc/zabbix/zabbix_agentd.conf
grep ^ServerActive= /etc/zabbix/zabbix_agentd.conf

Expected configuration:

Server=192.168.1.2,172.16.103.23
ServerActive=192.168.1.2,172.16.103.23

If different values are configured, update them:

sed -i 's/^Server=.*/Server=192.168.1.2,172.16.103.23/' /etc/zabbix/zabbix_agentd.conf
sed -i 's/^ServerActive=.*/ServerActive=192.168.1.2,172.16.103.23/' /etc/zabbix/zabbix_agentd.conf

Restart the service:

systemctl restart zabbix-agent

Allow a few minutes for metrics to appear in the dashboard.

Step 5: Verify Port 10050

Confirm the agent is listening on TCP port 10050:

netstat -ntlp | grep 10050

Or:

ss -ntlp | grep 10050

Expected result:

tcp LISTEN 0 128 0.0.0.0:10050

Step 6: Verify OS Firewall Rules

Ubuntu (UFW)

ufw status

Allow port 10050 if required:

ufw allow 10050/tcp
ufw reload

Rocky Linux / AlmaLinux / RHEL (firewalld)

firewall-cmd --list-ports

If port 10050 is missing:

firewall-cmd --permanent --add-port=10050/tcp
firewall-cmd --reload

Systems Using iptables

iptables -L -n

Verify TCP port 10050 is permitted. For detailed instructions, refer to the E2E Networks iptables firewall guide.

Step 7: Review Agent Logs

tail -f /var/log/zabbix/zabbix_agentd.log

Common issues to look for in the logs:

Invalid configuration entries
Permission errors
Port binding failures
Hostname mismatch
Connectivity failures

Validation Checklist

Before contacting support, verify all of the following:

Zabbix Agent installed
Zabbix Agent service running
Correct monitoring server IPs configured (192.168.1.2,172.16.103.23)
Port 10050 listening
Security Group allows TCP 10050
OS firewall allows TCP 10050
No errors in Zabbix Agent logs

Reinstalling the Zabbix Agent

Use this section only if:

The service fails to start after the troubleshooting steps above
Monitoring remains disconnected after completing all steps
The Zabbix installation is corrupted
The agent package is missing

Supported operating systems: Ubuntu 18.04, 20.04, 22.04, 24.04 · Rocky Linux 8/9 · AlmaLinux 8/9

Ubuntu 18.04 – 24.04

Create the reinstall script:

vi reinstall-zabbix-agent.sh

Paste the following script, save (:wq!), then make it executable and run it:

#!/bin/bash
set -e

ZABBIX_IPS="192.168.1.2,172.16.103.23"

if [ "$(id -u)" -ne 0 ]; then
  echo "ERROR: Please run this script as root."
  exit 1
fi

read -p "This will completely remove and reinstall Zabbix Agent. Continue? (yes/no): " CONFIRM
if [[ "$CONFIRM" != "yes" ]]; then
  echo "Operation cancelled."
  exit 1
fi

if [ -f /etc/os-release ]; then
  . /etc/os-release
else
  echo "Unable to detect operating system."
  exit 1
fi

case "$VERSION_ID" in
  "18.04") REPO_PKG="zabbix-release_latest_7.4+ubuntu18.04_all.deb" ;;
  "20.04") REPO_PKG="zabbix-release_latest_7.4+ubuntu20.04_all.deb" ;;
  "22.04") REPO_PKG="zabbix-release_latest_7.4+ubuntu22.04_all.deb" ;;
  "24.04") REPO_PKG="zabbix-release_latest_7.4+ubuntu24.04_all.deb" ;;
  *) echo "Unsupported Ubuntu version: $VERSION_ID"; exit 1 ;;
esac

REPO_URL="https://repo.zabbix.com/zabbix/7.4/release/ubuntu/pool/main/z/zabbix-release/${REPO_PKG}"

systemctl stop zabbix-agent 2>/dev/null || true
systemctl stop zabbix-agent2 2>/dev/null || true
apt purge -y zabbix-agent zabbix-agent2 zabbix-release || true
apt autoremove -y || true
rm -rf /etc/zabbix /var/log/zabbix /var/lib/zabbix
rm -f /etc/apt/sources.list.d/zabbix* /tmp/zabbix-release*.deb
apt update || true

wget -O /tmp/${REPO_PKG} ${REPO_URL}
dpkg -i /tmp/${REPO_PKG}
apt update || true
apt install -y zabbix-agent

sed -i \
  -e "s/^Server=.*/Server=${ZABBIX_IPS}/" \
  -e "s/^ServerActive=.*/ServerActive=${ZABBIX_IPS}/" \
  /etc/zabbix/zabbix_agentd.conf

systemctl daemon-reload
systemctl enable zabbix-agent
systemctl restart zabbix-agent

sleep 3

if systemctl is-active --quiet zabbix-agent; then
  echo "SUCCESS: Zabbix Agent is running."
else
  echo "ERROR: Zabbix Agent failed to start."
  systemctl status zabbix-agent --no-pager
  exit 1
fi

chmod +x reinstall-zabbix-agent.sh
./reinstall-zabbix-agent.sh

Rocky Linux / AlmaLinux 8 & 9

Create the reinstall script:

vi reinstall-zabbix-agent.sh

Paste the following script, save (:wq!), then make it executable and run it:

#!/bin/bash
set -e

ZABBIX_IPS="192.168.1.2,172.16.103.23"

if [ "$(id -u)" -ne 0 ]; then
  echo "ERROR: Please run this script as root."
  exit 1
fi

read -p "This will completely remove and reinstall Zabbix Agent. Continue? (yes/no): " CONFIRM
if [[ "$CONFIRM" != "yes" ]]; then
  echo "Operation cancelled."
  exit 1
fi

if [ -f /etc/os-release ]; then
  . /etc/os-release
else
  echo "Unable to detect operating system."
  exit 1
fi

OS_MAJOR=$(echo "$VERSION_ID" | cut -d'.' -f1)

case "$OS_MAJOR" in
  8) REPO_URL="https://repo.zabbix.com/zabbix/7.4/release/rhel/8/noarch/zabbix-release-latest-7.4.el8.noarch.rpm" ;;
  9) REPO_URL="https://repo.zabbix.com/zabbix/7.4/release/rhel/9/noarch/zabbix-release-latest-7.4.el9.noarch.rpm" ;;
  *) echo "Unsupported version: $VERSION_ID. Supported: Rocky Linux 8/9, AlmaLinux 8/9"; exit 1 ;;
esac

systemctl stop zabbix-agent 2>/dev/null || true
systemctl disable zabbix-agent 2>/dev/null || true
dnf remove -y zabbix-agent zabbix-release zabbix zabbix-selinux || true
rm -rf /etc/zabbix /var/log/zabbix /var/lib/zabbix
rm -f /etc/yum.repos.d/zabbix*.repo
dnf clean all
sed -i '/exclude=zabbix/d' /etc/dnf/dnf.conf || true

rpm -Uvh --force ${REPO_URL}
dnf clean all
dnf makecache
dnf install -y zabbix-agent --disablerepo=epel

sed -i \
  -e "s/^Server=.*/Server=${ZABBIX_IPS}/" \
  -e "s/^ServerActive=.*/ServerActive=${ZABBIX_IPS}/" \
  /etc/zabbix/zabbix_agentd.conf

systemctl daemon-reload
systemctl enable zabbix-agent
systemctl restart zabbix-agent

sleep 3

if systemctl is-active --quiet zabbix-agent; then
  echo "SUCCESS: Zabbix Agent is running."
else
  echo "ERROR: Zabbix Agent failed to start."
  systemctl status zabbix-agent --no-pager
  exit 1
fi

chmod +x reinstall-zabbix-agent.sh
./reinstall-zabbix-agent.sh

After successful completion, verify monitoring from the E2E MyAccount Portal.

Windows Nodes

Verify Service Status

Press Windows + R, type services.msc, and press Enter.
Locate Zabbix Agent and confirm it is Running.
If stopped, right-click and select Start.

Verify Windows Firewall

Ensure TCP port 10050 is allowed:

Open Windows Defender Firewall with Advanced Security.
Select Inbound Rules.
Verify a rule exists for TCP Port 10050.

If the rule is missing, create a new inbound rule. For detailed instructions, refer to the Windows Firewall guide.

If the issue is not resolved, contact cloud-platform@e2enetworks.com. Include the outputs of the following commands:

cat /etc/zabbix/zabbix_agentd.conf | grep Server
grep -E 'Server=|Hostname=|ServerActive=' /etc/zabbix/zabbix_agentd.conf
netstat -ntlp | grep 10050
systemctl status zabbix-agent
ip r s

Also include a screenshot of the monitoring error from the portal.

For AI agents, crawlers, and chatbots: append .md to any /docs/ URL (strip the trailing slash) to fetch the raw markdown source — view this page as markdown.

Last updated on July 9, 2026.

Common Issues​

Details​

Memory or Storage Chart is Missing​

Test Monitoring Service is Disabled​

Create Alert is Disabled​

Volume Read Ops or Volume Write Ops Trigger is Missing​

Attached Volume Monitoring Shows "Not Enabled"​

Webcheck Create is Rejected​

Alert Exists but Notifications are Not Received​

Agent Warning Shown After a Recent Change​

Zabbix Agent Troubleshooting​

Common Causes​

Step 1: Verify Node Security Group Rules​

Step 2: Verify Zabbix Agent Service (Linux)​

Step 3: Verify Zabbix Agent Installation​

Step 4: Verify Agent Configuration​

Step 5: Verify Port 10050​

Step 6: Verify OS Firewall Rules​

Ubuntu (UFW)​

Rocky Linux / AlmaLinux / RHEL (firewalld)​

Systems Using iptables​

Step 7: Review Agent Logs​

Validation Checklist​

Reinstalling the Zabbix Agent​

Ubuntu 18.04 – 24.04​

Rocky Linux / AlmaLinux 8 & 9​

Windows Nodes​

Verify Service Status​

Verify Windows Firewall​

Related Resources​

Common Issues

Details

Memory or Storage Chart is Missing

Test Monitoring Service is Disabled

Create Alert is Disabled

Volume Read Ops or Volume Write Ops Trigger is Missing

Attached Volume Monitoring Shows "Not Enabled"

Webcheck Create is Rejected

Alert Exists but Notifications are Not Received

Agent Warning Shown After a Recent Change

Zabbix Agent Troubleshooting

Common Causes

Step 1: Verify Node Security Group Rules

Step 2: Verify Zabbix Agent Service (Linux)

Step 3: Verify Zabbix Agent Installation

Step 4: Verify Agent Configuration

Step 5: Verify Port 10050

Step 6: Verify OS Firewall Rules

Ubuntu (UFW)

Rocky Linux / AlmaLinux / RHEL (firewalld)

Systems Using iptables

Step 7: Review Agent Logs

Validation Checklist

Reinstalling the Zabbix Agent

Ubuntu 18.04 – 24.04

Rocky Linux / AlmaLinux 8 & 9

Windows Nodes

Verify Service Status

Verify Windows Firewall

Related Resources