Archer C7 2.4 GHz wireless dies in 24~48 hours

This could well depend on local WiFi context, if you have a congested 2.4 network, then the default 'back-off' of signal strength on a channel with multiple competing APs will result in loss of working connectivity.
Try scanning for the least congested channel, then manually configure the AP to that channel, and also lock in the signal strength to a value that woks in your context. Max is not always best, as it just causes more headaches for all, best limit your strength to the coverage you need.

I've seen this since 17.01.x on various models of the C7. Guessing that the back-off values and/or algorithm get regularly tweaked, so plausible that the various build behave differently. Then again, could be something else.