I am using using 2x Billion 7402GX Routers to setup an IPSEC VPN between my Head & Branch Office. The VPN connection itself works fine, but after the VPN has been connected for an hour or so, the branch office cannot access the internet anymore.
Everything over the VPN works fine, I can ping both ways, RDP with the local IP's, but everything that comes & goes externaly doesn't work.
I thought it had something to do with the DNS setup of my branch office server. When the internet knocks off, I cannot resolve external names. eg: ping www.google.co.za does not resolve the IP. I can ping IP's.
Clients receive IP's through DHCP / DNS points to the Server (win2008R2) / Server ip is static and dns points to itself and the ISP's dns servers / ISP's DNS servers are setup as 'forwarders' in the servers DNS config aswell /
When I restart the router, everything works fine again.
Everything at the Head office works fine.
Any ideas? Please let me know if you need more info.