IGS very broken!

[symon_braunbaer]

Dear experts,

In one of our systems, IGS is very broken and we need to fix it, however we're out of ideas...
Transaction SIGS says it can't connect to IGS. The RFC destination doesn't work:

How can we register it ? The reginfo and secinfo files allow every connection. We have tried restarting the Gateway in transaction SMGW without any success.

When running the command:

rfcexec -a IGS.<SID> -g hostname -x sapgw01

the RFC starts working, but as soon as we hit Ctrl+C to exit the process, the RFC stops working again.
And even while the RFC is working under the influence of the rfcexec command, the SIGS transaction is
showing the following error:

We keep searching on the SAP Marketplace and on google, but we can't find a solution that could help us to 
fix IGS in this particular system. This is an S/4 Hana 2023 system running on Linux. Please advise, many thanks!

[symon_braunbaer]

Come on, nobody has an idea how to fix that ?? Really hard to believe!