AT&T and T-Mobile connections have different gateway controls and inbound reachability constraints for home VPN servers.
Before you change anything
This is a diagnostic entry point. The source supports the general check, not a confirmed root cause for your device.
What to check first
Was the test performed from a different network?
Record the exact model, hardware revision, firmware and recent change before adjusting settings. If you cannot answer the question, keep the cause open.
Narrow the likely path
| Observation | Next check |
|---|---|
| Client will not connect | Check profile, protocol and model firmware without sharing keys. |
| Server cannot be reached | Classify WAN addressing, CGNAT and firewall before port changes. |
| Tunnel connects without traffic | Check route, DNS and overlapping LAN subnet ranges. |
Decision after the first test
Identify provider equipment and WAN address, then separate VPN client use from inbound server hosting before changing passthrough or port rules.
Use a documented next step
Verify before escalating
After each change, repeat the exact failed task. If the result is unchanged, restore the previous setting and use the official support link for your exact hardware revision. Don’t assume a menu or capability from a related model.
Official sources
- T-Mobile 5G gateway network settings and limitations (full_text; checked 2026-11-01)
Check your exact US model, hardware revision, and firmware on the linked support page before changing settings.