Hi,
ThinLinc should work fine on Ubuntu 26.04, however the default desktop environment on this distribution (GNOME 50) has removed support for X11, which ThinLinc requires. We currently have a plan to support Wayland instead (see here), which will allow GNOME 50+ to be used in a ThinLinc session again. However, we generally recommend using other more lightweight desktop environments anyway such as MATE or XFCE, since these tend to give a better end-user experience in a remote desktop session. So if you haven’t already, please give these a try on Ubuntu 26.04 and see what you think; ThinLinc ships with predefined profiles for these desktop environments, so it should be sufficient to install them from the Ubuntu repositories without any additional configuration. Hope that helps!