I have the same issue with 8260 on 20.04. Without backports installed the wi-fi worked but there was often a very long delay when connecting to or loading a site. Ran speed test (google speed test) and there was a 15 - 20-second delay connecting to the server, but then good speed (around 40 MBPS) was reported. This was repeatable. Installed backports and selected it as the driver and the delay disappeared. Now connects instantly and reports the same good speed.
I have the same issue with 8260 on 20.04. Without backports installed the wi-fi worked but there was often a very long delay when connecting to or loading a site. Ran speed test (google speed test) and there was a 15 - 20-second delay connecting to the server, but then good speed (around 40 MBPS) was reported. This was repeatable. Installed backports and selected it as the driver and the delay disappeared. Now connects instantly and reports the same good speed.