I have RB433AH (not UAH), but in my case eth2 and eth3 is not working with v4.1. It was no problems with v4.0 RC1. I have found that this problem has something to do with switch option. I can see that both eth2 and eth3 are used in switch, but I have no chances to change something in switch - I get error that its not implemented. I asked for support request. Hope to get and answer from them.