unusable screen sharing / vnc protocol remote desktop control

I just did a RealVNC to a Mac in my basement (I used my Mac laptop to run the RealVNC viewer).

I have an eero 6E Pro mesh network. The basement Mac is connected to Ethernet via a 16 port switch to the eero router unit, and the Mac laptop running RealVNC Viewer was using WiFi and connected to one of the eero mesh nodes (not the router but one of the other nodes).

While VNC was not as responsive as macOS Screen Sharing between 2 Macs, it was only a few milliseconds of lag. Everything worked just fine in my home.

I connected to Mac_computer_name.local (as specified in System Preferences -> Sharing -> Computer Name) and it connected up just fine. I was even able to use my macOS username and password, as RealVNC understands macOS credentials. That is to say, I did not need to set an insecure VNC password.

I would expect a bit slower responses if I was at a coffee shop attempting to connect back to my home, as my ISP only gives me 6 megabits/sec out-bound speeds, and that is the direction all the screen repainting would travel over. But inside the house, it was really just fine.

Granted I would not want to play a fast twitch game via RealVNC, but for performing remote maintenance and light GUI activities it is perfectly acceptable to me.

I know a co-worker that has a company Mac which was kept in the office, and from home the used the company VPN to gain access to the company network, and then used RealVNC on their personal Windows PC to remotely connect to the work Mac and did software development via the RealVNC viewer window. Their work Mac had 2 external monitors and the 13" MacBook Pro monitor that were all being exported. At least the company's out-bound bandwidth was a lot better they what my ISP gives me 😁. So once the co-worker figured out all the connection details, they never reported any other issues using RealVNC to do their job.

I do not know.

Try booting your Mac into Safe mode

Boot macOS Safe Mode: hhttps://support.apple.com/guide/mac-help/start-up-your-mac-in-safe-mode-mh21245/mac

And then see if it still behaves strangely. Safe mode will not load any 3rd party additions, and you should be running just Apple software.

Or you could backup your Mac, then do a clean install and try it to the vanilla system. Or if you can create an external boot disk with a clean macOS install, or create an alternate boot partition on your internal disk, can try it that way without disturbing your existing customized system (still do the backup first, just in case).

Your an always restore you backed up data after you have performed the experiments.

It has been a while (years), but I was able to put TeamViewer into a mode where it allowed me to connect without a user at the remote system giving permission each time. I was able to use TeamViewer in this mode to remotely manage my Mom's iMac from 300 miles away. I no longer use TeamViewer and I do not know if this feature still exists.

Remote performance via VNC vs other screen sharing services has never been an issue, but rather feature compatibility has been the issue. Such as Copy & Paste issues, drag & drop files, etc... But whatever is on the screen should still be on the screen at the VNC viewer end of the connection.

Performance can be affected by low bandwidth up-link speeds, as most cable TV based ISPs give very slow up-link speeds, like 300 megabits down-link, and 6 megabits up-link speeds. Your VNC session needs to send via the up-link the screen and changes happening on the screen. That takes bandwidth, which many cable companies are not giving to their customers.

Also the more colors you include, the slower it is going to go. If you can limit your client so it asks for fewer colors, then that can reduce the amount of data that needs to be sent over a slow up-link.