Re: I'm so angry I can't think
I got no issues with 18.04 / kubuntu. Win10 is ok as well, it's display handling is much better. KDE/plasma at least scales betwen 1 and 2 kn a high dpi display, But W10 is superior on the dynamic side.
On the RDP front... why not just use . . . Well RDP, instead of VNC. Apt install xrdp. Viola, i can use msrdp from W10 to my ubu, or remmina from UBU to win. These days thats all pretty stable and seemless. Actually, for ubu server you can run LXDE skip the compositor, and use vanilla 16bit rdp, without beating up your client, or turn it up, use remoteFX, and have a pleasant experience if you've got the bandwdth. RDP on 2008+ is abysmal without a modern rdp client and good bandwidth.
W10/2012+ is decidedly more polished though, and even though I do run it, setting up openldap, and PAM, makes AD/fsmo roles, and cruft, look simple. At least until it breaks ;).
Most of the xrdp server stuff, fixed and got stable 3ish years ago. RDP accel is still hit or miss, on BOTH. Multi-display is cli invocation only.