KNX IP Gateway connection stopped working

Hi everyone,
it’s been a few days that I’ve been banging my head on this issue and this time I can’t seem to find a solution or even a technician in my city (Milan, Italy) that can come and have a look at my system.

This system has been working well for about 2 years although every now and then it would break and required some maintenance on my side. When that happened I’ve usually been able to diagnose the problem using ETS as well as Open Hab logs. This time I can’t even connect to the knx ip router using ETS.

The device itself is a ABB IPS/S 3.1.1 ip router and is connected and visible to the local network.
When I try to connect with openhab I get: timeout connecting to control endpoint /
When I try to connect via ETS I get something like gateway is unreachable.

I believe the device may have gone into some kind of lockdown and is not accepting any new connections. I tried turning it off and on again but it didn’t change anything. I thought of resetting the device but I don’t know how to do it and honestly I’m not sure if I would be able to configure it again afterwards.

I’ve sniffed the network packages with wireshark and the only two types of request that I have recorded so far are REQUEST_CONNECTION from the server to the router and a response from the router to the server that says ‘3671 port is unreachable’.

Any tips or hints that might help me move forward and find a solution to this problem?

Thanks for all your help!