I agree with you, i would try out General mode on the PowerConnect. console(config-if)# switchport mode general console(config-if)# switchport general allowed vlan add 2 tagged console(config-if)# switchport general pvid 1   Keep us updated.
hi there, i'am new on this forum and i have a trouble in this moment between a dell pc6248 and a Cisco router. The trouble is i lost conectivity in the VLAN 1 when i connect the router to a trunk port in the switch, however i have conectivity to VLAN 2 through this trunk link. The configuration on switch: interface ethernet 1/g48 switchport mode trunk switchport trunk allowed vlan add 1-2 exit interface ethernet 1/g43 switchport mode access switchport access vlan 2 exit On router interface fast 0/1 no ip address no shutdown interface fast 0/1.1 encapsulation dot1q 1 native ip address 192.200.3.1 255.255.255.0 interface fast 0/1.2 encapsulation dot1q 2 ip address 192.168.51.33 255.255.255.248 exit With the configuration above i lost conectivity with the host into vlan 1 - 192.200.3.x/24, but i gain conectivity to VLAN 2, when i connect the router to trunk port 48 in the switch. it means the trunk link work for the VLAN 2 but not for the VLAN 1. i have read about general mode port, where i can configure the pvid of the port like 1 (VLAN 1) and it would be the unttag VLAN (same as native in Cisco), and i can configure VLAN 2 like tagged, all of this in the same port. What do you think about this? Someone have configured something like this? Best Regards Erasmo PD: i write from chile, i apologise for my english. 
PowerConnect 6248 to Cisco router