Iphone 7 A1779 Japan NO SERVICE

I updated my phone to IOS 15, then it's made it slow and my service is intermittent. so I decided to restore and back up with itunes. Now my problem is when I activate it, its says "Unable to Activate" and Itunes say "The iPhone "iPhone 7" could not e activated because the activation information could not be obtained from the device." and now I found out that my IMEI can't be found when I check it in a Tool.

How to fix this? please help.