A few comments from my side:
Indeed it also observed that Satel can handle only one connection at a time. So if something else is connected, the integration won’t connect.
The integration does not read object names from Satel. You can give any name in HA, just make sure the output/zone/partion numbers match.
did I understand correctly that most likely the problem is not that I have IP blocking configured somewhere, but that after disabling one smart home system, the satel thinks that it still exists and does not let another system with another local IP?
If so, how to reset or reboot the satel, I have it powered by a battery and you just can’t turn it off, but I haven’t found anything like a reboot anywhere.
What I mean is that if two systems are trying to connect to Satel system only the first lucky one will get a working connection. So make sure the old system or something else other then HA is not trying to connect.
One way to do it is to change the port in Satel to something other than default 7094 and update it in HA as well. That way no other system knows how to reach Satel.
You can have either Home Assistant or Iridium working with Satel but both.
Does this integration work with Plus version of the Integra alarm panel e.g. INTEGRA 64 Plus ?
Yes, it does. I have Integra 128 Plus and it works fine.