Are there any how too's on more advanced wifi problems?

Let's start with something cheaper than "start over." Radio signal interference has been big factor in my wifi/bluetooth drop-out issues and, in my case, can absolutely be traced to location.

At home I seldom use my Macbook Pro or iPads at my workstation, preferring instead to doing important work on the iMac. I have few dropouts. The few I've experienced usually happen if I've left my iPhone SE2 almost under the iMac.

However, I volunteer as a host/docent for a local museum once a week. For that I take the Macbook Pro, my iPhone, and one of the iPads. That is when I see a lot of drops.

The volunteer desk is also "ground zero" for all the museum's tech. So, in addition to my Apple gear, there is a Windows desktop computer, the router/modem for our wifi, a wireless printer that also has bluetooth, the internet connection for the credit card machine, and the base station for the center's wireless phone handsets. In the room next door is a microwave oven and the conference phone system and a gob of power cables for phone, internet, computers and networking gear.

At home I seldom get dropouts; at the museum I get several a morning. Apple have addressed that issue in this support article:

Resolve Wi-Fi and Bluetooth issues caused by wireless interference - Apple Support

I don't know if this will help but there are some things on the list that I'd not thought could been an issue before.

At least review that article and the physical arrangement of you workstation before "starting over."

Do you have the same issues with this laptop at other locations than your home? If so, then it may point to a hardware or software issue with your laptop.

If the issue only occurs at home, the issue is likely some sort of interference or compatibility issue although a hardware or software issue is still a possibility. Keep in mind your other devices may be connecting using a different WiFi protocol or antenna on the router (some routers may have multiple WiFi antennas). Just because all those other devices are not having a problem does not mean you should avoid looking at your router (especially a power cycle) and interference issues. The laptop may just be more sensitive to a weak or noisy WiFi signal.

You can check the WiFi signal strength (RSSI) and noise levels plus the type of connection by Option-clicking the WiFi icon on the menubar. Signal levels (RSSI) should be somewhere between -30db and -60db (with -30 the stronger signal) while the noise level is usually around -90db.

I have seen some reports on these forums where users have mentioned having WiFi issues when using the laptop in Clamshell mode.

I have seen software issues affect the ability of properly connecting with WiFi so don't discount looking for software issues. Try booting into Safe Mode to see if that helps since it will disable third party software from automatically launching at boot and login.

Honestly, Wi-Fi setup is simple and straight forward enough and as such there are no "advanced" wi-fi problems. Please describe an advanced problem you're having. Everything you've listed in your post is what I see half the time with the other half being lack of expertise.

If the situation is bad enough, you may need to get different and/or newer equipment and just start over. I did that when I couldn't solve nagging problems and it was really good decision..

This falls under a “stuff the fake AT&T router and get a real router” stuff. I can recommend Asus. Good luck!