The PF box is a notebook with only one NIC(router-on-a-stick).

Port 7 is Tagged in VLAN5 and VLAN55. PVID is 5.

On PF box VLAN5 is defined as WAN with Dynamic IP, gets IP from the cable modem.

On PF box VLAN55 is defined as LAN with static IP. 

This is the configuration that worked/is working on the Netgear.

On DELL switch;

VLAN5 - port 1 Untagged, port 7 Tagged. PVID 5

VLAN55 - port 7 Tagged, ports 9-23 Untagged. PVID 55(9-23)

PF box does not configure Tagged or Untagged. It only allows for creating VLANS and assigning those VLANS to WAN or LAN. 

I ran show tech on the DELL 2824 and I see a couple of things that don't appear correct. I configured via the web interface and that may be part of the issue. I won't post all of the show tech results unless you feel you need them.

------------------ show vlan ------------------

Vlan Name Ports Type Authorization
---- ----------------- --------------------------- ------------ -------------
1 1 g24,ch(1-8) other Required
5 WAN g(1,7) permanent Required
55 LAN g(1,7,9-23) permanent Required

------------------ show interfaces switchport ------------------
Port : g1
Port Mode: General
Gvrp Status: disabled
Ingress Filtering: true
Acceptable Frame Type: admitAll
Ingress UnTagged VLAN ( NATIVE ): 5

Port is member in:

Vlan Name Egress rule Port Membership Type
---- -------------------------------- ----------- --------------------
5 WAN Untagged Static
55 LAN Tagged Static

Classification rules:
Port : g7
Port Mode: General
Gvrp Status: disabled
Ingress Filtering: true
Acceptable Frame Type: admitAll
Ingress UnTagged VLAN ( NATIVE ): 5

Port is member in:

Vlan Name Egress rule Port Membership Type
---- -------------------------------- ----------- --------------------
5 WAN Tagged Static
55 LAN Tagged Static

Classification rules:
Port : g9
Port Mode: General
Gvrp Status: disabled
Ingress Filtering: true
Acceptable Frame Type: admitAll
Ingress UnTagged VLAN ( NATIVE ): 55

Port is member in:

Vlan Name Egress rule Port Membership Type
---- -------------------------------- ----------- --------------------
55 LAN Untagged Static