openWRT 21.02.2 Causing Wireless Connectivity Dropouts on Archer A5 AC1200 v5.6 (Hardware Identical to Archer C50 v5)

Hey there, everyone! it's my first time making a post on here so I'll try to be as concise as I can. Thank you to everyone in this community and especially the devs for making such important software!

My system is a TP-Link Archer A5 AC1200 version 5.6 running openWRT 21.02.2 (from LuCi home page: OpenWrt 21.02.2 r16495-bf0c965af0 / LuCI openwrt-21.02 branch git-22.046.85957-59c3392). The hardware appears to be identical to the Archer C50 v5 and is running a MediaTek SoC MT7628AN "ver: 1 eco:2" (whatever that means).

I followed the instructions on this official guide in 2021 to install it because I really needed SQM to combat bufferbloat and it worked great for a long time. However, there was an issue that started occurring sometime last year where the Wi-Fi would just randomly drop out.

Every time this connectivity dropout occurred, I'd have to restart the router. What could be causing this? I'm trying to find the exact time that this happens again to check the system (and kernel???) logs. Should I upload those logs here? Could it be my Motorola SBG6580-G228 Surfboard modem combobox causing this issue? The Surfboard is old and I was thinking about replacing it. The Archer A5 is connected to this modem. However, if it really was the Surfboard, then why does the Archer's wireless AP just drop out/shutdown completely like that? The issue (most of the time, anyway) isn't that the Wi-Fi network doesn't have a connection to the ISP, it's that it shuts down completely.

Thank you for reading this and I appreciate any assistance and advice!