sbs 2011 server keep losing internet connectitivy

We are running sbs 2011 server every few days the server loosses inter connectitivy, we cannot access the server remotley or mail via the web.

I run the  SBS 2011 "Fix My Network Wizard" and it reports that an internet port mapping is missing, it then continues and reports the the problem was fixed".

Can anyone offer some assistance plesase.

we are using a linksys  e4200 routher upnp is enables and dhcp is disabled.

thanks

kurt

Thanks