Maybe try reconfiguring the 6100 as a bridge, and have the netgear handle PPPoE if that is required.
Many ISPs filter NETBIOS packets, so it is possible that the problem is due to such filtering, rather than to anything the 6100 is doing. -- AT&T dsl; Westell 2200 modem/router; SuSE 10.1; firefox 1.5.0.10