This might be long,,

We have two buildings. Each has its own ISP.

The buildings were connected using NannoBeam Antennas.... and all were on the same IP address net 192.168.1.X

Building one's gateway is 192.168.1.1 and building two's gateway is 192.168.1.2.

Our devices have grown to the point where, I think, we need to VLAN the network.  This is where we are a bit lost.

Our thoughts are that building ONE will be 192.168.1.x and building TWO will be 192.168.2.x.

That seems to be easy and it is set like that now and all is working

The one thing that is not working is the Library system.

We need some computers within 1.x to talk to the main Library database in 2.x through the antennas.

How can we set up the switches so that 1.x and 2.x can communicate with each other and 1.x still uses 1.1 for the gateway and 2.x still uses 2.1 as its gateway. Also block computers from sending and receiving DHCP requests to and from the other VLANs?

i hope this make since.

Thanks

Jason