Well to start, after the latest system update for Sony Xperia 1 III 61.1.A.9.128 I noticed the following couple of problems:

1) When I am in an area where the network coverage is weak, when the phone does not use 3g 4g but only the 2g network, it sometimes happens that the phone cannot make calls as if there is no signal, and also a message for a missed call arrives, or when I someone calls the phone starts ringing and stops after a second, as if someone just called me and hung up.

2) When the mobile data is turned on (wi-fi turned off) and after that it enters the following applications, there is a problem with the interruption of the internet.

1. Music player - play a song

2. Facebook - start a video(post) with sound

3. Instagram - start a video(post) with a sound

4. Youtube - start a video with sound

5. Viber video call

As I wrote at the beginning, I noticed these bugs after the software update. I have been trying to solve this problem for a week in the following ways:

- software reinstallation via Xperia Companion,

- restoring to factory settings,

- resetting network settings, returning apn parameters to factory values,

- despite all that, I took a new sim card, but the problem was still not solved.

After a week of trying to solve this problem, last night I was able to see exactly how this problem occurs, that is, what needs to be done to make this bug appear, and also what needs to be done to prevent this bug from appearing and what the problem is let me know if I do things to fix this problem.

All that needs to be done to detect this bug is the following:

Launch one of the apps I listed above and do the following:

Press the volume up button to the maximum volume level or press and hold once. After that, click a few more times, but you don't have to, and then reduce it by one click or a couple of clicks and repeat this several times. AFTER THAT THE 3G, 4G ICON DISAPPEARS FOR A SECOND, APPEARS AGAIN AND DISAPPEARS AGAIN AND SO MANY TIMES UNTIL WE REDUCE THE VOLUME TO A LITTLE MORE THAN HALF. AT THAT MOMENT WHEN THE 4G ICON DISAPPEARS, DATA TRANSMISSION IS TERMINATED AND THEN THE INTERNET DOESN'T WORK.

I NOTICED THIS PROBLEM FOR THE FIRST TIME WHEN I WAS TALKING ON VIBER ON A VIDEO CALL AND NOT KNOWING WHEN I VOLUME UP ALL THE WAY THE VIDEO CALL CUT OFF, AND THE SAME WHEN I WAS WATCHING A VIDEO ON YOUTUBE AND WHEN I VOLUME IT TO THE MAXIMUM VOLUME LEVEL IN A VERTICAL POSITION THE 4G ICON DISAPPEARS, AND IN A HORIZONTAL POSITION IT PUTS OUT THE MESSAGE AT THE BOTTOM OF THE SCREEN THERE IS NO INTERNET CONNECTION, AND AFTER A FEW SECONDS IT WRITES BACK ONLINE. THIS KIND OF NONSENSE AFFECTS THE USER EXPERIENCE A LOT.  WHEN YOU ARE WATCHING A VIDEO ON YOUTUBE AND EVERY MOMENT YOUR MOBILE DATA CUT OFF AND DURING A VIDEO CONVERSATION ON VIBER, YOUR VIDEO IS INTERRUPTED. I NOTICED THESE COUPLE OF BUGS, FOUND IN WHICH SITUATIONS THEY APPEAR AND WHAT TO DO TO PREVENT THEM FROM OCCURRING, BUT NEW PROBLEM EXIST IN THIS CASE.