it's hard to search for my following problem, so I just ask. Just as a first note it affects MorphOS and MacOS 10.5 on that machine and is thus not a MorphOS problem but maybe someone has an idea.
I have a MorphOS PowerBook 15,9 (MorphOS 3.11), a router (Fritzbox) and an Ubuntu Server (14.04). Some time ago everything was fine but now I cannot send or receive anything from/to the Ubuntu Server from/to my PowerBook. I can ping my router, other computer and anything in the internet but not my server. Also every other connection fails, e.g. ssh. Connecting from any other computer to my server works. I have forwarded the ssh port from my router to the server so I can connect from internet. If I use the internet address of my router the connection works, which means if the packets from the PowerBook are forwared by the router all connections work.
So my conclusion, the packets from my PowerBook are not accepted by the server or other way round. But this is new, it worked in the past. Any help?