Remember, WISP mode is typically routed, not bridged, so it will setup its own local network (e.g., 192.168.1.x), firewall, etc., behind the wireless bridge. You can imagine it as a “virtual WAN”. That means your PC should either be using DHCP (and have its DHCP lease renewed), or else a static IP from the WISP's local network (not the remote wireless network). Another potential problem is if the remote and local networks are using the SAME subnet (e.g., 192.168.1.x). If that’s the case, one of them needs to be changed (the WISP router is the logical choice in most instances).