Reach RS2 hasn’t worked with the MSM3 messages. There were no changes in the supported messages during the latest updates.
You can check out the full list of compatible RTCM3 messages in this thread:
It seems like the caster changed the RTCM3 messages that it sends to the rover which might cause the issues with connection now. Could you please share what RTCM3 messages your NTRIP caster works with?
