okay...
Network access:
For the amiga requires SAMBA (
download), its easy to setup and allows it to communicate with the Wintell pc's on your network
heres how
http://www.amigau.com/c-networking/samba.htm
OR / AND
Amiga Explorer read more (and download)
http://www.amigaforever.com/ae/
Gateway:
Well you allready have this, the ROUTER address is the Gateway
make sure that all the devices all share the same sub-net mask of 255.255.255.0 (should be what its set for)
this should help.