Receiving raw WNS fails after initial 20 minutes of modernstandby

Question

I'm testing raw WNS receiving during sleep on a battery powered windows PC which supports "S0 connected sleep state". Client app (UWP) can receive raw WNS until initial 20 minutes of modernstandby, but cannot receive after that.

Client app implements the registration of out-of-process background tasks triggered by PushNotificationTrigger ("IsNetworkRequested" property is set to true). This background task logs the time when it receives WNS. By configuring some settings (power management settings, registry and powercfg cmd, etc.), I could confirm that the background task can receive WNS shortly after it is sent even during sleep for 3 hours or more when connected by Wi-Fi.

But, if disable Wi-Fi connection and enable MBB (mobile broadband) connection instead, the background task cannot receive WNS during a sleep time of more than 20 minutes.

MBB case can be summarized as follows:

• When sleep exceeds 20 minutes, the background task receives WNS at the time it exits sleep (Or receive WNS a few hours later).
• When sleep is less than 20 minutes, the background task can receive the WNS at the time it was sent.
• When plugin AC, the background task can receive the WNS at the time it was sent

I expect that the background task always receives the WNS shortly after it is sent. It's achieved with a Wi-Fi connection. Is it possible to wait for receiving on MBB for the same amount of time as Wi-Fi connection?

Test procedure:

1. unplugged AC, only on battery powered
2. Enter to sleep
3. Wait 3 hour or 10/20/30/60 min
4. Send WNS from server
5. Wait 5 - 10 min
6. Exit sleep
7. Open log file and check recorded time (Test passed if the recorded time is a few seconds behind the time in step.4.)

Environment:

• 2 Laptop PCs
• Windows10 Pro (20H2/21H2)
• Sierra Wireless EM7430 / Sierra Wireless EM7565

Device Manager