Regarding wireless: I did several tests with 21.02.0-rc2 over a few days, and it works mostly good. Clients are an Intel 8265, another Intel AC (I don't have the exact model), and an old Android phone.
- the Intel 8265 gets 350 Mbit/s up and down with 80 MHz, and 260 Mbit/s up and down with 40 MHz
- the other Intel gets 350 Mbit/s down, but only around 50 Mbit/s up with lots of retransmits, not sure why
- coverage looks okay for both 2.4 GHz and 5 GHz
- changing channels for 5 GHz works, even with DFS (there is a DFS wait)
- no crash at all in 3 days
Big wireless issues as described before are probably caused by missing or wrongly decoded calibration data.