Netmetal AP disconnecting PPPOE clients...

Hello Everyone,
I am having a weird issue with one of my NetMetals. Here is my setup:
Base Server – RB1100AHx2
Tower – 2 Netmetals with 120 sector antennas
Clients – SXT 5 ac
I am using the base server as a pppoe server, the two radios are connected to a bridge using port 2 and 3, they are setup as ap bridge. CPEs are setup with pppoe client and are used are routers.
Everything was working fine until last night, pppoe connection on one of the AP got disconnected, and the log says Peer not responding. After a while I decided to reset the AP and restored the backup I had, I saw users get a pppoe connection but after a couple of seconds they lost pppoe connection again and got the same error on the log.
I then checked the registration table en the AP wireless interface and the user are connected to the AP. The wireless signal is good and everything.
I decided to go to the clients and check from there, I also saw that the wireless connection is good the the AP but the pppoe connects and then disconnects when I disable and enable it.
What I did next was to try to connect to the other AP, I was getting a fair signal -70. Once I connected to that AP the pppoe connection was established with no problems.
After troubleshooting and finding that the client connects to the other AP makes me think that there is something wrong with that radio, but everything that has to do with the wireless link seems to be working fine….
Has anyone experience this issue before?
Thanks

Do you use rstp at the Bridges?
I yes Turn it Off!