Link two separate networks

I run a small IT support business and we have a poor broadband connection speed. Recently our service provider reduced the cost of service to £5.99 and as we have two lines for the premises we decided to take up a second service primarily so that downloading on one service wouldn't effect the speed of the other.

The plan was to have customer pc's and repairs on one side often needing various updates and our own "working" connection unencumbered by the excessive downloads on the other.

We succesfully set up the customer side 192.168.0.* with a DHCP enabled ADSL router and on work side 192.168.1.* with a DHCP disabled ADSL router, Server 2008 DHCP disabled and fixed IP addresses pointing to the gateway 192.168.1.254 which as far as we can tell has kept us separate and connecting via our own ADSL connection.

FYI both Subnets are 255.255.255.0
Server currently has just a single NIC - two could be fitted if recommended

This seemed to have worked successfully allowing occasional access from client PC's to software located on the server - although the security implications are concerning as we obviously get virus infected PCs for repair.

We now want to enable VPN on the server and the setup requires that DHCP is turned on but this will mean having two DHCP servers on the same physical network.

What we want to do is maintain the separate subnets, make sure customers remain on 0.* and work 1.* but still have the option to access one from the other - that is unless someone advises the security of this is too risky as I guess a worm could get across subnet.

Simply typing this has help clarify the requirements in my own mind and I guess the advice I will most likely get is to have two separate nets with no link but if someone has a better alternative suggestions would be most welcome.

Thanks in advance

 

Simplest solution is not to do VPN at the server, but at the router instead. That way you won't have to enable the second DHCP. You may have to upgrade your router, or better still buy two hardware firewalls and use their VPN facility. Small SonicWall, Watchguard or even Netgear firewalls will do the trick. My personal favourite has been to pick up cheap 2nd hand Watchguard firewalls on ebay.co.uk and use them.