After an hour of running up and down and exchanging cables I found the following pattern:
- PC to Amiga connection with long cable: Not working
- PC connection to router with long and small cables: Ok
- Amiga connection to router with small and long cables: Ok!!
- Amiga to PC connection with small cable Ok!!!
My guess, after a sudden flash, is that one of the cables must be crossover, the other isn't. The router works ok with any, I've read more recent routers detect crossover cables, probably the shortest one.
:pint: