The OS4 networking stack, "Roadshow", is ridden with old bugs and cannot be updated because Hyperion cannot be bothered, it is currently way behind the OS3/68k build.
Heck, there even was the OS4.1 FE update 2, without any Roadshow updates, from what I understand because of lack of communication by Hyperion, so Olsen didn't manage to prepare it in time.
Now, if Roadshow for OS4 could be sold as a separate product, like it is on 68k...
For what it's worth, my OS4 systems also have the problem you describe, only with totally different hardware, and also other software, for example AmTelnet.