Wifi has internet access, wired NIC has access to a private network without gateway. When I connect the ethernet cable, the wifi disconnects from the hot spot after a few seconds. If I try to reconnect the wifi, it connects as expected and disconnects the next second by itself.
I have a Dell M4700 Laptop running Windows 7 64-bits. My WiFi adapter is Intel Centrino Ultimate-N 6300 AGN and my wired NIC is an Intel 82579LM Gigabit, but I also have the same behavior using a USB adapter and XpressCard adapter.
That happened in two different wifi routers and I have another laptop that works fine on both networks and it also runs Win7 64.
I have tried to disable the IPv6 protocol, Cisco CDP, IP helper service. I've also tried to use Intel wifi manager and Windows wifi manager, always with the same result. Any ideas on how to fix this?