The RB4011 stops Wifi communications, when a client disconnects

RouterOS Wireless Networking
1

Hi!
We have a RB4011iGS+5HacQ2HnD-IN router with 6.46.4 firmware and factory default settings.
My problem is that when multiple wireless client connected and one disconnected suddenly (for example, it shuts down) the communication with other client failed. This can happen on both 2,5 and 5 GHz interface. If I ping the clients on 5GHz connection, the response time increase from 1-2ms to 50-70ms for 5-10 seconds, when I switch off one client.
If there was any communication (I tested with 800kb/s broadcast stream) , then all communication stopped and the traffic decreased to 0. With the 6.45.1 firmware, the clients often disconnected in this situation, and the log said: “disconnected extensive data loss”.

My question: is it setup or hardware problem?
I also tried a RB2011UAS-2HnD-IN router with 6.37.3 firmware and an Archer C5 router, there was no problem.

2

I would correct my post. When i tested with broadcast stream, the multicast helper was enabled. I found the issue occorred, when the removed client get unicast stream. With the unicast stream, this issue occurre a lesser extent on the other router.