Remote Viewer connection fails: WebRTC and firewall troubleshooting

Android

Your Remote Viewer session may fail immediately after starting if your network firewall or policies block the WebRTC traffic required for live remote control. This article helps you diagnose and resolve the issue.

Before you begin

Remote Viewer uses WebRTC technology, which is separate from Esper's management connection. A device appearing Online in the Esper Console does not guarantee Remote Viewer will work — the two channels use different ports and protocols.

Symptoms of WebRTC/ICE negotiation blocking

Remote Viewer sessions fail immediately after initialization, even though the device appears online
The session appears to start (projection permission is granted, Knox remote control activation succeeds) but drops during the live connection stage
The failure occurs consistently across all devices on the same network
Remote Viewer works successfully on the same devices when connected to a different network
Rebooting the device does not resolve the issue

Step 1: Confirm the network is the issue

Test Remote Viewer on a device connected to a different network (mobile hotspot, home Wi-Fi, or different office network). If it works, the problem is network-specific.
Verify that the failure affects all devices on the affected network, not just one device. This confirms a network-level block rather than a device-specific problem.

Step 2: Collect and review device logs

Pull device logs from an affected device using one of these methods:
- Via Esper Console: Go to Devices & Groups → [Device Name] → Logs
- Via ADB: Run adb shell logcat
Search the logs for ICE negotiation failure messages. Typical messages include references to ICE candidates, STUN/TURN, or WebRTC connection failures.
If you do not see ICE-related failures, the issue may be different — contact Esper Support (see "Still need help?" below).

Step 3: Work with your IT team to unblock WebRTC traffic

Share this information with your network or IT team and request they verify or enable the following:

WebRTC ICE/STUN/TURN traffic over UDP and TCP
Outbound UDP on high port ranges (typically ports 10000–65535) used for media relay
Connections to Esper's TURN/STUN infrastructure

This is especially important if your organization manages a locked-down network (schools, correctional facilities, healthcare systems, or government networks) with strict egress filtering.

Step 4: Test the fix

After your IT team confirms or adjusts firewall rules to permit WebRTC traffic, attempt a Remote Viewer session from a previously affected device without rebooting.
Verify that the session opens and remains connected.
Confirm with your IT team that all affected devices on the network are now accessible via Remote Viewer.

If the issue persists

Firewall rules confirmed but sessions still fail: Contact Esper Support and provide your device logs, the ICE failure messages, and your network configuration details. Your support agent may evaluate alternative remote access methods or advanced configuration options.
Only some devices on the same network are affected: Investigate device-level differences such as Knox version, Esper Agent version, or OS/firmware level. Contact Esper Support if you identify a pattern.
Network is strictly locked down: Contact Esper Support to discuss alternative remote access methods or tenant-level configuration options.

Still need help?

If you have confirmed that WebRTC traffic is unblocked but Remote Viewer sessions still fail, or if you need help troubleshooting, contact Esper Support. include your device logs, any ICE failure messages, and a description of your network configuration.