I'm using OnePlus 5 on Android 10. Notifications never stopped arriving, but if I tried to connect to the Internet (e.g. Browser, Banking App), the app connection failed (timed out). I'm pretty sure these are Push Notifications. As an example, I received notification from my Bank of a recent deposit, but the banking App timed out when I tried to log in to verify this. Also the phone is receiving Facebook notifications of recent birthdays, including today's date, but can't open the Facebook App.
I've tried this with both WiFi & Mobile Data and see the same behaviour.
I connected the phone to my laptop with USB and ran an adb shell on the phone proving Internet access with a successful adb shell ping 8.8.8.8. I then thought I had an explanation for the behaviour: DNS lookup failing. However, repeating a similar adb test adb shell ping google.com, this too was successful, proving DNS resolution working!
I'm now out of ideas, and reached the limit of my Android knowledge, so I wondered if anyone here could help. I expect a factory recovery would fix the issue, but I don't want to lose all my apps & my valuable data! Any suggestion on how to fix it without losing my old data?
Edit: I still haven't resolved this issue, but have made futher investigations:
The notifications are Push notifications from the Internet, not locally generated. Verified this by turning off Mobile Data & WiFi for some time, and when I turned it back on again, the phone received a bunch of backlogged notifications.
I side loaded "Ping Tools" apk and installed, with this I could successfully "Ping" sites like amazon.com, cisco.com demonstrating DNS is working and the phone is able to receive small ICMP packets. However putting these domains into a browser gives error "ERR_CONNECTION_TIMED_OUT"
I also tried connecting the browser to local IPs 10.0.0.x (Router, NAS) which should present the login page for these devices, but again get the error: "ERR_CONNECTION_TIMED_OUT", despite being able to successfully ping both devices from the phone.
Again, I've run out of ideas, so any further suggestions greatly appreciated.
Edit 2:
It's been a long time since I posted my original question and I still haven't resolved it. However, further experiments show the behavior is weirder than ever:
I noticed that I was receiving WhatsApp notifications AND the actual WhatsApp messages. Not only that, I could successfully send WhatsApp messages & even make a WhatsApp voice call!!
Now this may be just WhatsApp specific black magic because I still cannot browse any website and all my other apps cannot access their back end servers on the Internet.
It's almost like my phone has some weird firewall configuration that is allowing WhatsApp & Notifications but nothing else. And if this were the case, I've no idea how to investigate it further, so, as before, any helpful suggestions welcome. I'm now really keen to understand what is going on here.
