From the “tool for one thing and it does it well” category:
Several weeks ago (it might have been after I installed Big Sur), I stumbled upon an issue with my Macbook Pro 16 inch. Although I technically should have had a very good WiFi connection (TX rate up to 1300 MBit), my WiFi traffic (also within my LAN) sometimes kept crawling to TX rates between 20 and 50 MBit. That was “fine” for light internet usage, but not for work and it certainly was not feasible to work with my NAS.
Yesterday, I stumbled upon this article at a German tech blog (Warning: in German). The article deals with the MacOS 11.1 release. Incidentally, the author mentioned those exact same WiFi issues which apparently can be related to the feature of unlocking your Mac with your AppleWatch. If you enable this feature, the MBP can be pretty much useless for serious WiFi work especially in combination with a Fritz!Box which is a very popular WiFi router in parts of Europe. The author expressed his hope that 11.1 might help with this situation. I do not know, if 11.1 remedied the issue, but disabling unlocking my MBP with my AppleWatch made my MBP fly again.
I thanked the author for bringing up this issue because I was not aware of it. The author recommended yFi then. It was the first time that I heard about yFi.
Long story short: yFi monitors your device’s TX rate so that you know about the max possible data rate all the time. It shows up as a menu bar item. So, if your throughput is crawling at ridiculously low speeds, it might be the case that your device is being connected with a ridiculously slow TX rate to your router. So, what does this tool give you what your (or at least my) router does not? Real time (!) monitoring of the theoretical TX rate (not the actual throughput).
It is a small tool that does nothing else than that. It launched 4 months ago in the App Store. It is free as in free.
If the TX rate falls below a threshold (that you can define), you can choose that yFi gives you a message or that it automatically instructs your device to reconnect to your WiFi network.
If you have WiFi issues, too, or if you are just interested in a little free tool that monitors your TX rate, yFi WiFi companion might be for you.