Teamviewer is a no brainer, cross platform, to handle my retired dad's computer on the other side of the country and/or customer's screens on the other side of the world.
Teamviewer hasn't worked for me in years. At some point it started to claim I was using it for commercial purposes, and even after convincing support that this wasn't the case, I've never been able to maintain a connection for longer than a minute since.
Pretty much will refuse to work if you have a static IP Is they claim that's commercial.
I gave up on it for the same reason. Kept getting flagged for commercial use when all I used it for was ham radio stuff and helping my parents.