The message you provided could also point to a failed negotiation between the client and server - perhaps due to a self-signed certificate or an expired certificate.
Some time ago had issues with krdc on Wayland so I created a template script.
Among other things it uses a flag /cert:ignore to counteract the self-issued certificates on windows servers. The script is based on the commandline options described in the freerdp documentation
As there is a solution in above mention report you could use the script and add to the parameter list of script by inserting the pamameters in the beginning of the line
The line for wayland inject
/usr/bin/wlfreerdp /tls-seclevel:0 /timeout:80000 [...]
The line for xorg
/usr/bin/xfreerdp /tls-seclevel:0 /timeout:80000 [...]
If you don’t feel like scripting you can add the parameters in server properties on the Advanced tab
Screenshot
