Before I switched to nixOS, I used Arch, I had a lot of trouble on it with my WiFi, it regularly dropped connection with the laptops builtin WiFi card and I could not get it up again without rebooting the system.
Therefore I plugged in an USB WiFi that I had lying around. That worked well and without any problems with Arch.
Today in nixOS none of the devices has dropped the connection as the builtin did in Arch, though connection is slow most of the time.
The NICs connect to the AP with 50 or 100 MBit/s respectively corresponding with their nominal speeds.
Though real transfer is a lot less than that. most of the time, even when downloading large files, actual transfer is a sawtooth from 150 to 250 KiB/s (per KSysMon).
Every once in a while transfer will linearly increase until ~9MiB/s is reached (takes about 10 to 15 seconds), keep that speed for another 20 to 30 seconds and then instadrop back to the old saw tooth. Staying there for 30 seconds or many hours…
Uploads seem to be always at ~7MiB/s, which corresponds to my my ISPs connection cap.
USB NIC: Bus 003 Device 006: ID 07d1:3c0a D-Link System DWA-140 RangeBooster N Adapter(rev.B2) [Ralink RT3072]
builtin: 04:00.0 Network controller: Intel Corporation Wireless 7260 (rev bb)
Can someone of you provide some tips how to get steady speeds?