"Firmware gets updated, sometimes old drivers don't work when newer ones do, and vice versa."
So?
Asus puts out a firmware that loses compatibility with existing drivers and its the driver's fault?
Your logic escapes me.
If Asus had a pattern of reliability with the 5 ghz channel part of this code fine, I'd consider the firmware the stable aspect and my driver the variable that needs to be addressed.
Is that the case? Asus has been rock solid with the 5 ghz piece?
Why no, it isn't.
... Fault is a little irrelevant here, smart butt. The only one who cares that your router/network is malfunctioning, is you.
The fact of the matter is that sometimes certain router firmwares don't work well with certain NIC drivers. I assure you, ASUS doesn't give a damn whether or not the specific driver you want to cling to works with the router or not, so the burden is on you to try other drivers if you want a functioning network. If NONE of the drivers work, then it's ASUS' problem.
Until you're actually willing to try to fix the problem (which includes trying other drivers) then the problem is yours to deal with.
And actually yes, some of the older drivers were solid on the 5GHz frequency.
But anywho, it's your problem. No worries, I won't bother trying to help you again.