Wifi 2.4G packet loosing except torrent when downloading


I have 2 routers Asus rt-ac58u (ipq4018) with openwrt 19.07.4 in dumb AP mode, setup by manual. Also setup roaming between these 2 AP. Main router mikrotik.

Today, I run torrent on laptop connected to 2.4G wifi, the torrent was downloading, but other internet things didn't work. E.g.,run ping to main mikrotik router, the icmp packet came to mikrotik and it's sent an answer, also came to AP checked by tcpdump, but it did not came to laptop in time. I checked, about 10 ping packets from 30 were failed. When torrent was stopped, the ping started to work with 100%, the same for dns and others packets. I don't understand what can be the issue. Could someone assist, I think you need my config to understand, which one?

Thanks a lot.