The new Intel AX201 adapter has 2×2 MIMO (twice the number of antennas for 2 times the WLAN speed if the router supports it). If the Surface device goes into standby mode, the Dynamic SMPS feature deactivates one antenna and the other antenna goes into low power mode. The error, however, is that after waking the device from standby mode, the second antenna is no longer activated and the other antenna remains in low power mode. This results in greatly reduced speeds and higher latency.
- Go to the hardware manager -> network adapter -> Intel AX201 -> Advanced -> MIMO power save mode -> Change “Auto SMPS” to “No SMPS”. While this resulted in the bug occurring less frequently, only changing the setting to “Static SMPS” (-> disabling MIMO) eliminated the problem entirely for me.
- (Optional) Go to the Windows Settings App -> System -> Power & Sleep -> When my PC is asleep and on battery power, disconnect from network -> Change “Never” to “Always”
In the workaround, Auto SMPS is disabled for the WLAN adapter, turning off the power saving. This results in higher power consumption, but prevents the speed drop. The second workaround is from the Settings page, where the network connection settings are adjusted.