Have a 2830 connected to adsl2 from bt Internet. Have 3 pc all working ok for 3 months. This week cannot access any web page a after the google page. Clicking on maps, YouTube on google page works and can ping sites as well.

I can VPN into router and it worked with VPN bridge to remote site

Can you check if is a DNS issue?
Try change to google ones

I did change dns to 8.8.8.8 and 8.8.4.4 but had no change. I had to put it in the LAN general setup.

Can not think right now something else but if i was you ... will check if something has changed at the 2830 of the firewall , User Management >>User Profile, CMS section, also scan your pc with any anti-malicius & anti virus programs ... if did installed with out your knowlege any thing malicius ... Strange can browse only the google sites

There are 3pc,s on network plus iPhone through wireless. Same problem on all