2 port gateways not working after switch replacement

While you were replacing your switch did you take the opportunity to update the console software? If so did you go from before 3.2 to 3.2.0 or later? Are your old gateways Net2 or Net3?

The reason I ask is that in 3.2 the Net2 protocol was removed...

Nope.  All I did was change out the switch.  I can still put the old one back and everything works fine.  I suspect the problem has something to do with DHCP, because the gateways are not getting a valid address.

Do you know which device acts as DHCP server in your network? It could be the console, but it could also be the old switch (depending on model of the switch) or something else entirely. This of course would only make a difference, if your gateways are set to use dynamic IP addresses rather than static.