[SOLVED] Network gone after a few min,

[Vorms]

Hello,
I have a similar problem.
I have no wifi dongle but ethernet cable.
I have no usb device at all.
The only special is I have 2 vlan, one for local area with nas and internet and the other for ip tv.

If I wait a long time the network is no longer usable.
Ping for the local router is ok but ping for http://www.google.com doesn't work.

So when I want to use the system I have to shut down before...

Any help will be welcome.

Thanks in advance.