To chime in on the recent issues, I have similar trouble of my own.
I just bought a SL3 13", i5 model so with the AX201 chip. Other users report their wifi being slow
after wake up, mine however was always slow and still is slow at all times, no matter if I fully turn it off and on again etc.
Fully resetting Win10 didn't do anything either. Neither did reinstalling the drivers etc.
The suggested workarounds (MIMO, Sleep & Power-settings) yield no different results.
It's really frustrating, a new machine that I really enjoyed, marred by this massive issue. While people report they get about 10% of their max. available speed, I can confirm for my SL3 that this is on the high side when it has a good moment, usually it's
in the 3-5% range (that's 2Mbps for me), coupled with abominable latency (2 seconds and more).
I contacted the support, they remote-controlled my SL3 and well.... They proceeded to uninstall any and all Network devices from within device manager, needless to say my connection was cut immediately leaving me with an SL3 that couldn't connect to any
network. Luckily after a reboot it found a driver for the Wifi module - still, what did they think was going to happen?
I then contacted the support again, this time someone else asked me to perform some checks and let the Surface Diagnostic Tool run, no issues - of course, it has a connection, Win10 thinks it's fine but the driver is defunct.
If anyone has another suggestion what to try, that'd be very welcome!
This needs to be fixed asap. I would really like to keep this SL3, but I'm afraid I can't hold out any longer than a week, I need a machine that works, and if I have to go back to a Macbook Pro then so be it, but I'd actually prefer the SL3.
Best regards