Remote Viewer disconnects at session establishment: check network, firewall, and APN configuration

Android

Improved title: Remote Viewer disconnects on connect — fix network, firewall, or APN

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When a Remote Viewer session disconnects immediately after you start it, the session stalls at the "Connecting…" phase and never displays the device screen.

Why this happens

Remote Viewer establishes a relay connection between the Esper Console and the Esper Agent on your device. If a firewall blocks the required outbound endpoints, or if a cellular device has an incorrect APN, the relay handshake cannot complete and the session drops. This is almost always a network-level restriction, not a problem with the device or the Esper Agent itself.

Step 1: Isolate the network as the cause

1. Connect the affected device to an alternate network — a mobile hotspot or a Wi-Fi network without corporate firewall restrictions.
2. In the Esper Console, navigate to Devices & Groups → [Device Name] → Remote Viewer and start a new session.
3. If the session connects successfully on the alternate network, the issue is confirmed to be in the primary network environment. Continue to Step 2.
4. If the session also fails on the alternate network, the issue may be device-specific. Skip to If this doesn't resolve it.

Step 2: Whitelist the required Esper endpoints

Remote Viewer requires specific outbound URLs and ports to complete the relay handshake. If any are blocked, the session will not establish.

1. Review the full list of required URLs and ports in the Esper Firewall Requirements documentation.
2. Share that list with your IT or network team and request that all listed URLs and ports be whitelisted on the site network where the affected device is deployed.
3. After the firewall rules are applied, wait five minutes for changes to propagate.
4. Return to Devices & Groups → [Device Name] → Remote Viewer in the Esper Console and start a new session.

Step 3: Verify and correct APN configuration (cellular devices only)

If the device uses a SIM or cellular connection, an incorrect or missing APN will prevent it from reaching Esper's relay servers even when the device shows a signal and appears connected.

1. Work with your carrier or network administrator to confirm the correct APN settings for the SIM in use.
2. Verify the APN configured on the device matches those settings exactly — including APN type, proxy, and port fields if required by your carrier.
3. Correct any mismatched or missing values.
4. After saving the APN changes, navigate to Devices & Groups → [Device Name] → Remote Viewer and start a new session.

Verify: A successful Remote Viewer session moves past "Connecting…" within 15–30 seconds and displays the live device screen. If this happens consistently on the primary network, the issue is resolved.

If this doesn't resolve it

If Remote Viewer still disconnects after whitelisting all endpoints and correcting the APN:

• Confirm with your network team that the firewall rules are active and applied to the correct network segment where the device is located.
• Retest on the alternate network to determine whether the problem is network-specific or device-specific.
• Collect the following before contacting Esper Support:
  • Device serial number and the device name shown in the Esper Console
  • Network type in use (Wi-Fi, cellular, or both)
  • Carrier name and APN settings if the device is on cellular
  • Confirmation of which Esper firewall endpoints have been whitelisted
  • A screenshot or description of the exact point at which the session drops

Contact Esper Support with the above information to expedite diagnosis.

Still need help?

If Remote Viewer continues to disconnect, submit a support ticket and include your network configuration details, firewall rules, APN settings, and the exact error message or timing of the disconnection.