Just wanted to mention, C7 v4's 2.4GHz band is not buggy. Works just fine. My two units haven't had a single problem in that regard, first one bought in ~2017. Uptimes of nearly two months before the usual brownout/power cut. Different SoCs and hardware (QCA9563 vs QCA9558)
v2 is the model with an unreliable 2.4GHz band, yours is a v2 IIRC. There has been some progress on that in State of C7 v2|v5 in 2021, there's a tweak in the later posts that has resulted in stability for some people.
This also contains @sammo 's "iw phy phy1 set txq memory_limit 8388608" as a startup script (see /etc/uci-defaults/99-ath9k-set-txq-memory-limit which creates /etc/init.d/ath9k-set-txq-memory-limit to run every startup to adjust the memory limit and avoid the "slowly dying 2.4 GHz WiFi").
Have a look.