Certain servers kill wifi adaptor - not on VPN client

[dagadog 5]

I'll start by adnitting that this sounds really odd to me so I would welcome a more rational explanation.

 

I have a dual-homed server which connects to AirVPN via the Netherlands servers, and acts as a gateway for my LAN  Connection to the Internet is via an ordinary cable ISP router. I never have a problem connecting.

 

Every so often (several weeks apart), however I notice two symptoms on a Windows laptop, connected to my LAN over wifi.

1. Access to certain websites which normally require just a password requst captcha verification.
2. The wifi dies on my laptop, and won't connect to any access point on my LAN (either internal or external)

Logging on to my server and restarting the VPN service fixes both problems. I can understand the first one (shared IP being used for nefarious purposes) but what's going on with the WiFi?