2 edge routers in same rack need lan communication

So 2 Ubiquity UDM Pros in the same rack. Separate isp link for both.

I need them to communicate locally. Not over the wan (that would be silly they are right next to each other)

I did not choose this arrangement, before you ask. I was hired and the guy things "this provides better segregation" he's a good guy, but now I need to make it work.

So the Ubiquity interface is hot garbage. But forget that.

I do have a CCNA, so I knew to try giving an interface on both an IP and then connecting them and useing static routes. I also tried a static route with interface names and not IPs.

Well no dice. Before I bang my head against the Ubiquity UI anymore I just want to know this is the correct way to go about this.