remote desktop software - different platforms

[lightman47]

Preface:
A few years ago I used to use 'TeamViewer Free' to help out an older, fellow retiree with his Windows PC. I may also have used it to help another person once or twice. TeamViewer decided I was using it in a commercial setting and discontinued my free usage. Inquiries to 'their supreme arrogance' resulted in demands to sign & mail an agreement of their terms (that I never violated!!). Rather than printing/signing/taking to the U.S. Post Office and trying to figure out postage, I emailed that I agreed to all their terms. They couldn't be bothered to even reply one way or the other.

I am 75; my ever-more-forgetful buddy is 83. This morning, I drove 40 minutes each way, to discover that he was merely 'in the wrong folder' in Thunderbird.

Problem -
I run RHEL 8; he runs Windows 10 (until he succumbs to Windows pestering for 11). I investigated AnyDesk and a few others, but even $24.99 (US) per month is obscene for the few times I'd need it - perhaps 0-6 times per year.

Question:
What remote desktop options are out there for both platforms (RHEL/Windows) that might help me to avoid driving that distance.

Thank you - as usual, no rush!

[TrevorH]

Remmina supports RDP and VNC but both would require the far end to open the correct port in the firewall to allow access. Ports 3389 and 5900 are the standard ones but can be changed. In either case the firewall should be set up to lock down access to both the source ip and destination port.