How do I find the device ID of Android Phone

Support Android
1

I am starting up Syncthing and it asks me to enter the device id of the remote device which in my case is an android smartphone. How do I find this id. It says it’s your IMEI but it is not taken

2

When you open the menu (in the Syncthing app on Android) on the left-upper side (the hamburger-menu), somewhere in the middle there’s an item Show device ID.