The filename extension .tar usually implies this file is being used to the Access Point from Lightweight Mode (LWAPP) to Autonomous Mode (or vice versa via TAR archive upload).
where you found it (e.g., a website URL, a line of code, or a physical label) will allow for a more precise explanation. hardware brand that might use this naming convention? ap3g2k9w7tar1533jpn1tar better
Look for the vendor’s release notes. Search for 1533 and jpn1 . Better typically means: The filename extension
Do you have a bricked 3700? Share your console log in the comments. a website URL