Are you familiar with this discussion? A few brave people are trying to solve/find a workaround for the wifi issues for WRT3200ACM/WRT32X.
They've currently been able to track down the problem and remedy the issue by replacing the current mac80211, with an older one (5.7.5), in a 21.02.1 build. If it works for master as well, maybe this is something we could try out here too?