Remote Viewer fails to connect or is slow for location-specific devices: firewall and backend issues

Android

Title: Remote Viewer fails to connect or times out for devices at one location

When Remote Viewer consistently fails to connect or takes an unusually long time to establish a session for devices at a specific physical location, those sessions either drop immediately or hang until they time out.

Why this happens

Location-specific Remote Viewer failures are caused by one of two things: firewall or network policies at that site are blocking the ports and protocols Remote Viewer requires, or the Esper backend is holding a stale session record for the device that prevents a new session from being established. Because the failure affects only devices at one location, the root cause is almost always in the local network path or a backend state tied to those specific devices.

Before you start

Collect the following before working through the steps below:

The serial numbers or Esper device IDs of every affected device
Confirmation that unaffected devices are on a different network or physical location
Details about the affected network — for example, whether it is a corporate LAN, campus network, or enterprise Wi-Fi with a proxy or SSL inspection layer

Steps

Confirm the failure mode. In the Esper Console, navigate to Devices & Groups → [Device Name] → Remote Viewer and attempt to start a session. Note what happens: an immediate failure points to a stale backend session state, while a long timeout that eventually drops points to a firewall or network blocking issue. This distinction determines which step to prioritize.
Check that the device shows as online. In Devices & Groups → [Device Name], confirm the device status is Online. If the device is offline, Remote Viewer cannot connect regardless of backend or firewall state — resolve the device connectivity issue first.
Request a backend session refresh from Esper Support. If the device is online but Remote Viewer fails immediately, the Esper backend may be retaining a stale session record for that device. Contact Esper Support and request a Remote Viewer session refresh, providing the affected device IDs. After the refresh is applied, wait 15–20 minutes before retrying — this allows the backend to fully clear the previous session state.
Retry the Remote Viewer session. Navigate to Devices & Groups → [Device Name] → Remote Viewer and attempt a new session. A successful session should establish within 30 seconds. If the session still times out rather than failing immediately, the issue is in the network path and the next step applies.
Audit the local network and firewall configuration. Work with your network team to verify the following for the affected location:
- All outbound ports required for WebRTC, TURN, and STUN relay are open — refer to the Esper Firewall Requirements documentation for the full list
- No SSL inspection or deep packet inspection (DPI) proxy is intercepting Remote Viewer traffic
- If devices at the location connect to more than one network or SSID, egress rules are reviewed for all of them — not just the primary network
Test across multiple devices and sessions. After both the backend refresh and the firewall review are complete, initiate Remote Viewer sessions on at least two affected devices and confirm each session establishes within 30 seconds. Testing multiple devices confirms the fix is consistent and not device-specific.

Verify: Remote Viewer sessions on all previously affected devices should establish within 30 seconds. If sessions are stable across multiple devices and multiple attempts, the issue is resolved.

If this doesn't resolve it

If sessions still fail after the backend refresh and firewall rules have been confirmed as correct, contact Esper Support with the following information:

Full Esper device IDs for all affected devices
A description of your network topology at the affected location, including ISP, any proxy or VPN in use on the device or network, and whether SSL inspection is enabled
Esper Agent version from Devices & Groups → [Device Name] → Device Info
An ADB bug report captured from one of the affected devices during a failed Remote Viewer attempt

Still need help?

If Remote Viewer connectivity issues persist, submit a support ticket and include your device location, firewall configuration details, and whether the issue is intermittent or constant.