When I (and presumably my users) first start up or log in to my computer I can't get internet access until several minutes after logging in. Internet pages like serverfault.com will time out. During this time I can access internal web servers. Sometimes pinging the gateway seems to fix the problem.
I'm using Windows 7 on this machine with wifi, and the problem seems limited to the wifi network, which is on a separate vlan. The wired network does not share the problem, but I know it's not the wifi connection itself because the internal sites work.
The wifi access point is attached to a 3Com 4200 switch, with the port set for vlan 2 untagged, vlan 1 tagged. The 4200 has a fiber connection to a 3Com 4900SX fiber switch that acts almost as a router here. The fiber connection is vlan 1 untagged vlan 2 tagged at both ends. The gateway is then attached to a different 4200 (vlan 1 untagged, vlan 2 tagged) that has a similar fiber connection to the 4900SX.
vlan 2 has 192.168.8.0/22 IPs, vlan 1 has 10.1.0.0/16 IPs. The 4900SX has an interface for both vlans (10.1.1.1/192.168.8.1), as does the gateway (10.1.1.5/192.168.8.5). There is one dchp server for both vlans on the same switch as the gateway. It chooses a dhcp scope based on the interface used by the 4900sx to forward the dhcp request.
There is also a network access list on the 4900sx set to deny all vlan2 traffic to any 10.1.x.x host, with exceptions made for a few servers, including dhcp, 4900sx, and the gateway.
I think that about covers it. Any ideas on why internet access would be delayed like this?