That is the RemoteRig dynamic DNS server address and has no real relevance.
All I can say is that if a system was working before and all of a sudden stopped working due to a SIP error,
than the problem never lies with RemoteRig. Most people assume that is the problem, but they should look
at the environment. Something must have changed, e.g a router, something with the internet provider, a cable
fell out, etc. You have eliminated IPv6 as a culprit, but you need to carefully look at the other components until
you find the problem. You may also wish to try your system from another control location to verify if the problem
is at the control or radio end.
73,
Mitch DJ0QN / K7DX