My Android phone is currently hooked up to my internet via tethering, and when I first switch it on and turn tethering on, browser works perfect, fast and normal, then after say 2-3 minutes the browser just stops loading things and I get:

"This web page is not available
The connection to xxxxx was interrupted."

Not once does my internet connection on my phone drop out, and I can browse using the phones internet during the period it won't work on my laptop, so why do I get this? is tethering a timed period before it auto switches off? or have I got a setting wrong? all sleep settings are turned off on my phone so I know that isn't an issue.