I have RB433AH with ROS 4.2 with ethernet problem.
All my interfaces are in a bridge. One wireless interface for uplink, 2 wireless interfaces for connecting clients and etheret connected to other AP (tp-link / ubnt ). Dhcp is not getting(sometimes cilent get the dhcp ip, but in most cases it dosent) throug ethernet port, I have tested it with ubiquiti bullet M2 and tp link tl wa 501g.
Go to the site where you have the Mikrotik. Set your laptop to automatically get an address and connect to one of the bridge ports. Does YOUR laptop get an IP address and can you surf? If yes, then the problem is most likely not the routerboard, and you should look at your cables, AP and clients.
As a further test, take a couple of clients’ laptops and connect them directly to the bridge ports as well. Make sure that they can get IP addresses. You have to narrow this down to where the problem IS. DHCP either issues an address or it doesn’t. It doesn’t work sometimes and then not others.
Make sure that you don’t have the DHCP pool set too small (i.e. you have more clients than you have addresses available) and make sure the clients are set to automatically get a DHCP address. I run an ISP and you wouldn’t believe how many clients just don’t know how to do this or simply wail and moan and gnash their teeth until you come and do it for them.