EXPERT RESPONSE
The symptoms that you describe sound suspiciously like both Off1 and Off2 use the same IP subnet.
If a single device has two connections to the same subnet, one of two things will happen: Either one connection will have a lower route cost than the other, or routes will be ambiguous and unpredictable. For example, if your wired LAN connection has a lower cost, the wireless connection will always be used whenever it is active. However, if both connections have the same cost, some packets may be routed to the wired LAN and others to the wireless network.
This isn't necessarily a problem unless there is a reason that you want traffic to be routed over one connection and not the other. That's exactly what might be happening if you have two completely disjointed networks that use the same IP address range. For example, suppose your Ethernet connection has the static IP 192.168.1.4 and wants to send traffic to the Off2 server at 192.168.1.5. When your wireless connection isn't active, no problem -- your computer routes the packet through the Ethernet connection. But then you activate your wireless connection and it gets the dynamic IP 192.168.1.100. Your computer may decide to send that packet through the wireless connection, because it is also a valid route to the 192.168.1.0/24 subnet --- possibly even a preferred route. At this point, you won't be able to reach computers on the Off2 wired LAN, even though you are physically connected to it.
If this is the cause of your problem, the solution is simple. Just reconfigure the Off1 access point/router to use a different IP subnet and assign dynamic IP addresses from that subnet. For example, if Off2 uses static IPs in the 192.168.1.0/24 subnet, then Off1 can use the 192.168.2.0/24 subnet to avoid overlap. This will eliminate the routing problems described above by eliminating any ambiguity, letting your computer send traffic out the right connection to reach destinations in both networks at once.
However, there is still one further consideration: which connection should be treated as the default route? That is, when your computer tries to send traffic to a destination that's not on either your wireless network or your wired LAN (e.g., a server on the Internet), where should that packet be sent? Because you don't have a router in Off2, the answer is almost certainly the access point/router in Off1. This means that when you statically configure your wired LAN connection, you should not specify a default gateway. When your wireless connection gets an IP address, it should also get a default gateway address --- the local address of the Off1 access point/router.
One final hint: You can always see your computer's routing table by opening a Command Prompt window and typing "route print" -- type "route --h" for instructions on how to use this command.
For more information on subnetting and IP addressing:
 View this tip on how to subnet.
Test your subnetting skills with this interactive quiz.
View our IP addressing and subnetting guide.
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