vnc server fixed resolution

Hello everyone,

This is my last resort.

I have searched the internet everywhere using different search engines as well.

I am using Redhat 7 where I activated a vncserver (since it comes pre-installed).
using the following service:

[Unit]
Description=Remote desktop service (VNC)
After=syslog.target network.target

[Service]
Type=forking
# Clean any existing files in /tmp/.X11-unix environment
ExecStartPre=/bin/sh -c '/usr/bin/vncserver -kill %i > /dev/null 2>&1 || :'
ExecStart=/usr/sbin/runuser -l wvleider -c "/usr/bin/vncserver %i -geometry 1680x1050 -depth 32"
PIDFile=/home/wvleider/.vnc/%H%i.pid
ExecStop=/bin/sh -c '/usr/bin/vncserver -kill %i > /dev/null 2>&1 || :'

[Install]
WantedBy=multi-user.target

as you can see there is a -geometry parameter that is set to 1680x1050. this is the resolution i want the client to use no matter what client uses the VNC.

So far i have found out that xrandr is used within RedHat to change the resolution in an active session, meaning that it should be configurable somehow..

xrandr provides me some resolutions as preset, i tried to remove all resolutions i find unnecesary but xrandr does not allow me.

does anyone know how to fix the resolution server-side?

Thanks in advance!