Performance hog on TP Archer C7?

My router (TP link Archer C7) does this thing every random bit, that it starts dropping packets and my connection-sensitive applications (company VPN, world of warcraft) get the link dropped. I think I triangulated my issue to the router (through mtr in terminal - my main system is Manjaro). I have nothing running on the connected 2 PCs that would exhaust its performance (no torrent or the likes). My connected devices are 1-2 PCs, 1-2 phones, 5 sonoff basics (they shouldn't communicate a whole lot either, and they are routed through a secondary router in a secondary network) and a switched off smart TV. My real time graphs in LuCi show a jump in 1min load from the steady ~50% to 75% around the time the packets keep dropping.

I have 1 dyndns service and 1 uhttpd service running on the router. Nothing is open from a private IP so it is probably nothing ddos-related. No network drives, no nothing. I am connected on the 2,4 Ghz radio, Signal / Noise is -50...-65/-95 dBm on my laptop, there is no other router on the same or nearby WiFi bands that this router is working on.

My question is, how can I check what is the culprit on my router?

ssh connection to the router and then running "top"?

if indeed the reason is a cpu spike, you should see which process is causing it

The culprit is likely dodgy 2.4GHz drivers. Archer C7 OpenWRT port never really worked well on 2.4. There are many threads about this. One of them: Archer C7 V2 - Massive Problems

Basically, 2.4 works with few device but if you load it enough it will start dropping packets or stop sending packets but stations are still associated. This persists until reboot.

Disable 2.4 and use 5GHz only.