Updates freezing

I started to do an automatic plugin update today on one of my sites and it just hangs there, doesn’t update, then my site is down on ‘maintenance’ mode. This is the 3rd or 4th time it’s happened. I have to go into FTP to delete the .maintenance file to get my site back. I have multiple sites, all the same host, and no other issues.

Any ideas on why this happens and how to prevent it from happening again?

And just know I’m a baby/still learning on the technical stuff, so use simple terms please! Thanks! ??