I have had to open port 8080 on the firewall for one client. Thanks to Comodo ONE support agent, Ethan, for his help. c1-support@comodo.com
Ilker, the support case is #ETZ-838-73460 if you want to see more detail. There is still however an issue that the internal IP address of the device is not shown on the RMM console.
I opened mine both ways, it was on a testing network without any firewall rules. I started to lock her down some, and the console would not sign in, opened port 8080 and it worked. Unless it was a fluke, I did not try with it blocked again.