Slow web pages could be the result of dns server timeouts. Your router is probably getting the dns servers from your Internet provider. (Logging on to the router should tell you the routers dns server IP address).

The PC's could be getting their dns server IP address either from your Server or the 2700HGV router. Disconnecting your server from the network and connecting a PC to the router should test this premise.

Take your server out of equation and see if Internet access and webpages speeds up. later test your speed here ScanMySpeed.com