Bridge Ubiquity Power Beam M5 and Rostelecom?

Question

network hardware

The essence of the issue is as follows, there is a connection to Rostelecom, through a radio bridge on the Ubiquity RV M5 400.
One RV is connected to the RT switch, the other is in my Mikrotik. I receive IPTV and the Internet from Provo.
For more than a year everything was fine, but now, after half a year, problems began, on the provider’s side, the port on the provider’s switch often began to fail, and as a result, they simply turn off my port to me, explaining that a loop appears on my port and hangs all of them switch. Moreover, if the multicast is turned off, then everything works fine. After rebooting the port at Provo, everything is fine for a while and then again. So the question is, can the radio bridge itself make a loop? As I understand it, to get a loop, roughly speaking, it is enough to loop two ports with a patch cord on one switch. But how can this be? On the RV that I have, a switch with a TV and a router are connected, which distributes the Internet around the house.
I didn’t change the settings on the RV for all the time, I only updated the firmware on the RV a couple of times, the speed in the radio channel is 300Mbps, the network to their switch works without problems.
The provider says that there are problems with my equipment, but I can’t understand what could happen.

Answer 1

Have you done any settings on Mikrotik? Maybe he is flooding back to the ISP, which is why his ISP equipment eventually blocks.

Answer 2

Asus stood before him and it was the same, I replaced it with Mikrotik and nothing has changed. I turned on STP on the bridge, which is on the provider's side, so I'm watching, it can help. The loop appears when multicast is running. I'm already starting to sin on one of the consoles.