Delayed Notifications and Calls

I called my carrier and they said they didn't had any such issues before, and that from carrier side everything is working properly. I also went abroad for a month before, and even after changing carriers, during the trip, the problem persisted. I don't think the problem is from carrier side and even they stated that everything is working properly from their side.

Any other solutions?

Update: I found a similar old thread, there it was asked if you use apple watch. I do use apple watch, is it watch issue?

Delayed notifications - Apple Community

It’s been 20+ hours, anyone any solutions?

Calls as in calls over internet such as google duo calls, whatsapp calls. It’s not an cellular issue as it persists during WiFi also. Even imessage gets delay.

Gentle reminder.

No solutions, nearly 2months