diagnostics: System → Diagnostics with a network test probe; RTP_PORT_START/END

The server checks itself (public IP, DNS, local networks, phone ACL, SIP transports, free audio
ports) and says how to fix each problem. A quick or complete network test asks the probe
(apps/probe, own image) to test this server from outside: HTTP/HTTPS, SIP over UDP/TCP/TLS, the
browser phone's /ws, sampled audio ports. The probe only tests the address that asks.
The audio port range comes from RTP_PORT_START/END (default 10000-20000).

.env.example

@@ -14,3 +14,5 @@ APP_UID=1000
 APP_GID=1000
 LOG_LEVEL=info
 TRUST_PROXY=true                     # true when behind Caddy/nginx
+RTP_PORT_START=10000                 # call audio (UDP), both ends included: open this range on the
+RTP_PORT_END=20000                   # firewall and router. Two ports per call; 200 is plenty for a small office