Hi I have similar problem but not network related.
tLDR: fh2_setup.exe on the 2.56 ISO does not work on 32bit OS. Can a dev provide a 32bit compatible exe?
long version:
I had 2.55 and used the 'update' feature within the launcher, after a long wait, I was able to play 2.56 multiplayer without issue. Very neat feature actually.
Then I had to delete/re-install game for some other reason but this time decided to download the full 2.56 iso instead, as opposed to using 2.55 ISO and using the launcher updater, however, when i mount the 2.56 ISO I get "is not a valid win32 application" which suggests that fh2_setup.exe on the iso is 64bit only. fh2_setup.exe on the 2.55 ISO worked perfectly fine.
My question is, is there a 2.55 > 2.56 patch? (i.e. the file downloaded by launcher seperately available)?
While I could mount 2.55 again and use the the launcher updater a second time, I actually deleted the 2.55 iso to make room on my HDD + The updater is very slow for me (despite my network being fast) thus a 2.55 > 2.56 patch would be ideal here.
I doubt 2.56 will be recompiled because (only) I insist on using XP 32bit, nevertheless as already said, I have played 2.56 online with XP 32bit via 2.55 via launcher updater route without problem in the past.