ZyXEL P660R-D1 - Netbios Filter
Netbios is used for windows shares, by default the router will block this between the LAN and WAN.
You can disable this from the Web Interface:
Network -> LAN -> Advanced
CLI
To disable the filter (allow netbios)
sys filter netbios config 0 off
To enable
sys filter netbios config 0 on
To display:
sys filter netbios disp
To test from linux:
smbclient -L host
Will either fail/timeout or ask for a password...