[archived] 0.8.X images from ayufan; Mate DE + video / 3d acceleration

[Neo2018]

Hello pine64,

My hardware, software >
| OMV 4.1.20-1 Arrakis | RockPro64 4GB | Linux 4.4.167-1161-rockchip-ayufan-g6f1664023387 | NAS Casing | PCI-e to Dual SATA-II Interface Card |

I do not know 100% when that happened, either after the kernel update  from 4.4.132-1059 (or higher of 0.7.12 build, I do not remember what I had) to 4.4.167-1161, or OMV update from 4.1.19-1 to 4.1.20-1. I guess after the kernel update.
No remote desktop connection anymore. Installed plugin openmediavault-remotedesktop from omv-extras.

Code:

:~# dpkg -l | grep desktop
ii  desktop-file-utils                                                 0.23-1                                   armhf        Utilities for .desktop files
ii  gsettings-desktop-schemas                                          3.22.0-1                                 all          GSettings desktop-wide schemas
ii  libgarcon-1-0                                                      0.4.0-2                                  armhf        freedesktop.org compliant menu implementation for Xfce
ii  libnotify4:armhf                                                   0.7.7-2                                  armhf        sends desktop notifications to a notification daemon
ii  openmediavault-remotedesktop                                       4.0.1                                    all          Remote desktop plugin for OpenMediaVault.
ii  xfce4-panel                                                        4.12.1-2                                 armhf        panel for Xfce4 desktop environment
ii  xfdesktop4                                                         4.12.3-3                                 armhf        xfce desktop background, icons and root menu manager
ii  xfdesktop4-data
:~# dpkg -l | grep xrdp
ii  xorgxrdp                                                           0.9.1-9+deb9u3                           armhf        Remote Desktop Protocol (RDP) modules for X.org
ii  xrdp

Code:

:~# systemctl status xrdp
● xrdp.service - xrdp daemon
  Loaded: loaded (/lib/systemd/system/xrdp.service; enabled; vendor preset: enabled)
  Active: active (running) since Fri 2019-03-29 13:39:56 CET; 4h 42min ago
    Docs: man:xrdp(8)
          man:xrdp.ini(5)
 Process: 6382 ExecStop=/usr/sbin/xrdp $XRDP_OPTIONS --kill (code=exited, status=0/SUCCESS)
 Process: 6408 ExecStart=/usr/sbin/xrdp $XRDP_OPTIONS (code=exited, status=0/SUCCESS)
 Process: 6395 ExecStartPre=/bin/sh /usr/share/xrdp/socksetup (code=exited, status=0/SUCCESS)
Main PID: 6414 (xrdp)
   Tasks: 1 (limit: 4915)
  Memory: 588.0K
     CPU: 669ms
  CGroup: /system.slice/xrdp.service
          └─6414 /usr/sbin/xrdp

Mar 29 13:39:55 RockHomeServer systemd[1]: Starting xrdp daemon...
Mar 29 13:39:55 RockHomeServer systemd[1]: xrdp.service: PID file /var/run/xrdp/xrdp.pid not readable (yet?) after start: No such file or directory
Mar 29 13:39:56 RockHomeServer systemd[1]: Started xrdp daemon.
Mar 29 13:43:05 RockHomeServer xrdp[7226]: (7226)(-148815344)[ERROR] Cannot read private key file /etc/xrdp/key.pem: Permission denied
Mar 29 13:43:05 RockHomeServer xrdp[7227]: (7227)(-148815344)[ERROR] Cannot read private key file /etc/xrdp/key.pem: Permission denied
Mar 29 14:34:03 RockHomeServer xrdp[9731]: (9731)(-148815344)[ERROR] Cannot read private key file /etc/xrdp/key.pem: Permission denied
Mar 29 14:34:03 RockHomeServer xrdp[9732]: (9732)(-148815344)[ERROR] Cannot read private key file /etc/xrdp/key.pem: Permission denied

Alternatively, installing a vnc server failed.

Question:
1: How to fix the problem with the remotedesktop?
2: How do I reset the kernel to 0.7.14 build?
3: How do I alternatively install vncserver / tightvncserver?

many thanks!