I am in a similar situation. After I followed: https://forums.nomachine.com/topic/connection-fails-on-headless-client
i see this in my nxserver.log
59951 59951 2021-01-11 17:50:22 636.537 NXSERVER Starting LS 7.0.211 and services.
59951 59951 2021-01-11 17:50:22 636.720 NXSERVER System information: Manjaro Linux, standalone.
60020 60020 2021-01-11 17:50:27 045.210 NXSERVER User 'admin' logged in from '10.4.255.131' using authentication method NX-password.
60054 60054 2021-01-11 17:50:39 236.988 NXSERVER WARNING! NXRedis: timeout for command evalsha which is 10 has been reached.
60054 60054 2021-01-11 17:50:49 248.245 NXSERVER Previous message repeated 1 time
60054 60054 2021-01-11 17:50:49 248.425 NXSERVER WARNING! NXRedis: failed twice connection to db.
60054 60054 2021-01-11 17:50:49 248.561 NXSERVER ERROR! NXRedis: Cannot get output for command: evalsha after resending.
59951 59951 2021-01-11 17:50:49 268.346 NXSERVER ERROR! NXFrameBuffer failed to start.
60020 60020 2021-01-11 17:50:49 269.620 NXSERVER ERROR! Received error from nxserver --daemon nxFrameBuffer error while starting
60020 60020 2021-01-11 17:50:49 341.401 NXSERVER User 'admin' from '10.4.255.131' logged out.