HP 2920 and Sonicwall NSA 4500 - Weird Routing Issue

Just looking to see if there are any known issue's here.  Really odd one.  Was having an aging Enterasys stack replaced in a remote office with a HP 2920.  Site has a Sonicwall NSA 4500.  All my other sites have comparable hardware (NSA's, Procurves/HC3).  Note: No running-config below, as I did not grab before taking offline.

Quick Topology (for sake of simplicity, this setup as tried):

HP 2920 -
Sonicwall -
Cisco Router for MPLS -
Data VLAN:
VLAN interface IP on HP:

Devices on the Data VLAN point at for gateway.
HP has
ip route
ip route x.x.x.x (where x.x.x.x is the remote subnets across my MPLS)
IP routing is enabled.
All tagging is assumed correct.

My end users cannot reach the internet.  They can reach anything that is on a separate subnets* on the HP.  They can traverse the MPLS to other sites via the gateway.  So we are routing on the HP, but not to the Sonicwall?

Sonicwall does have the proper return routes for the subnets, pointing back at  (ie, uses  Also, the HP has the same IP as the old Enterasys.  

Some oddities:
Reboots of the HP and sonicwall will return internet access for a short period
Odd entry in the HP's arp table :  000000-000000
(with no port)
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I would suggest that you confirm that the switch port that the Sonicwall is connected to is in vlan 10.

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JamesonJendreasAuthor Commented:
Yeah, the uplink is in a port that is untagged in VLAN 10.
Do you see the mac address for on the Sonicwall and the mac address for on the HP? If yes can you confirm that the MAC addresses are correct. Also ensure that Proxy-arp is disabled on the interfaces of the SOnic-wall, HP and Cisco on vlan 10
Benjamin Van DitmarsSr Network EngineerCommented:
did you add a route in the sonicwall for the way back like gw

else the firewall doesn't know the way back to because this network is not know.
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