Since replacing my router with an Asus RT-AC68U1, I ran into an odd issue where my VoIP phone no longer registered with my provider VoIP.ms1.
I didn't clue in immediately that it was due to the router (and firmware) change, and I was about to reach out to the support team but decided to check their FAQ2 as it was suggested I do so prior to starting the live chat session.
As it turns out, there is an incompatibility with the Tomato firmware and the Linksys/Cisco SPA1121 I use.
To resolve,
- Navigate to your Tomato router at http://192.168.1.1 and log in.
- Navigate to Advanced > Conntrack/Netfilter