Each workstation appears to be able to ping the router and also a website address such as www.google.co.uk
successfully; however Internet access is intermittant, with some workstations connecting and others not being able to i.e. displaying the usual 'page cannot be displayed' error. It seems almost as if the connection is so slow that it times out most of the time, although email appears to be fine.
For reference, the anti-virus / security software is Norton Internet Security 2004 and the PC's are all of reasonable specification running Windows XP Pro.
Changing the computers DNS settings from 1) auto to 2) primary; sbs server IP address / secondary; router IP address to 3) primary; router IP address / secondary; sbs server IP address, seems to have no effect at all on the PC's that cannot access the internet at present. The router shows a constant Internet connection with automatic DNS and Public IP and this was originally set to DHCP ( rather than using the preferred option of server based DHCP ).
The SBS Internet & Email Connection wizard however cannot automatically configure the router. Selecting the 'manually configure router' is the only option that allows this SBS wizard to complete; however if DHCP is then switched off on the router and switched on via the SBS 2003 server, then the computers seem unable to renew their IP address from the server, despite DHCP seemingly being configured correctly on the server with an active scope.
Any advice on the best way forward to simply achieve reliable Internet Access for all PC's, with basic connectivity to the server, would be greatly appreciated.