I had my upgrade last weekend, from 300 to 500mbps. However after the upgrade, i couldnt even get back my previous max speed using 5ghz, nothing has been changed in the setting. At last, i changed the width in 5ghz to 20/40/80 (was 20/40)only i could get 450 and above but not everytime (better than when 20/40, i can only get max of 330+ using 5ghz), i also fixed the wifi channel for 5ghz now. Still monitoring the performance.

But am still concern what is the root cause that i cannot get the previous max speed after the upgrade since nth has changed in the setting?

Modem is he silver colour one. Router is AX73. Lan connection no issue at all. I have set my wifi setting for 5ghz to 20/40/80 and fixed a channel, i think the performance improved.

It happens to me for my 300Mbps to 500Mbps fsu last few weeks ago. Speed is up and down for 5ghz.The problem is nth in the settings has been changed during the upgrade and the 5ghz speedtest cant even reach previous 300 max speed. No issue for lan connection, 500+ w/o any issue. .After that, i tried to set the bandwidth for 5ghz to 20/40/80mHz (was 20/40) and fixed the wifi channel only the speedtest can exceed 450 (not everytime) but definitely better than before.