Time on iPhone is incorrect

Go to Settings/General/Date & Time. What is the time zone? And is Set Automatically on?

Go to Settings/General/Date & Time and turn on Set Automatically. This will sync the time on your phone to your carrier’s network time.

If you prefer manual setting then turn it off and enter the correct time.

Turn off set automatically and set the time yourself.

When it’s on automatic the time comes from your cellular carrier, so check with them.

Setting the time zone manually removes the inconvenience of incorrect time but does not resolve the underlying problem.

Nevertheless, the carrier is unable to solve the problem. Attempted solutions included "Reset All Settings." All to no avail. They are involving Apple now.

There are suggestions on other websites that this is a bug, and that it began appearing with iOS 11.

Yes, Set Automatically is selected. As I state above, I followed the procedures listed in pertinent support document. The only way to get the time zone correct is to set it manually to Mountain Daylight Time. Set Automatically states "Etc/GMT -1," though in fact the displayed time is GMT +1.

Does not work for me. Neither does the procedure outlined in this support document. My phone (6s; iOS 13.5.1) insists that the time is exactly 7 hours later than the correct time.