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I am using Raspian Stretch and I can not set the resolution of my desktop when using VNC headless.

I am using Real VNC because it comes by default (I have it configured there).

I have no monitors plugged in.

I have tried all the suggestions here

Currently I have the following saved in /boot/config.txt

hdmi_force_hotplug=1
hdmi_ignore_edid=0xa5000080      
hdmi_group=2     
hdmi_mode=16

but still it looks like it boots into 640x480.

When I try to set this from the Raspberry Pi Configuration GUI, no options are available (only "Default - preferred monitor settings").

When I do not make these changes to config.txt I can set the monitor resolution from the GUI but still no changes take place.

Please let me know if you have a solution to this issue.

2

I followed the instructions on RealVNCs troubleshooting page.

In brief,

  • Open the Raspberry Pi configuration application ('Start' > Preferences > Raspberry Pi Configuration)
  • On the system tab, click the Set Resolution.. button
  • Choose the resolution you want
  • Reboot

I did this all in headless mode via a VNC session on a fresh Raspian Stretch install, using VNCViewer 6.0.1 on Windows.

Perhaps you aren't given any resolution options because you have already forced a resolution - have you tried editing config.txt to set the video mode back to default?

For reference, here's my /boot/config.txt file:

# For more options and information see
# http://rpf.io/configtxt
# Some settings may impact device functionality. See link above for details

# uncomment if you get no picture on HDMI for a default "safe" mode
#hdmi_safe=1

# uncomment this if your display has a black border of unused pixels visible
# and your display can output without overscan
#disable_overscan=1

# uncomment the following to adjust overscan. Use positive numbers if console
# goes off screen, and negative if there is too much border
#overscan_left=16
#overscan_right=16
#overscan_top=16
#overscan_bottom=16

# uncomment to force a console size. By default it will be display's size minus
# overscan.
#framebuffer_width=1280
#framebuffer_height=720

# uncomment if hdmi display is not detected and composite is being output
hdmi_force_hotplug=1

# uncomment to force a specific HDMI mode (this will force VGA)
hdmi_group=2
hdmi_mode=16

# uncomment to force a HDMI mode rather than DVI. This can make audio work in
# DMT (computer monitor) modes
#hdmi_drive=2

# uncomment to increase signal to HDMI, if you have interference, blanking, or
# no display
#config_hdmi_boost=4

# uncomment for composite PAL
#sdtv_mode=2

#uncomment to overclock the arm. 700 MHz is the default.
#arm_freq=800

# Uncomment some or all of these to enable the optional hardware interfaces
#dtparam=i2c_arm=on
#dtparam=i2s=on
#dtparam=spi=on

# Uncomment this to enable the lirc-rpi module
#dtoverlay=lirc-rpi

# Additional overlays and parameters are documented /boot/overlays/README

# Enable audio (loads snd_bcm2835)
dtparam=audio=on

This corresponds to a display resolution of 1024x768 @ 60Hz according to the config.txt documentation

Here's the options that are presented in the resolution settings: enter image description here

I find the drop-down a bit touchy, you need to click and hold to get the list to display correctly.

  • Yes and there are still no options to set resolution. – Startec Sep 25 '17 at 18:47
  • Does the GUI not provide options, or do they not apply when you select them? – andrew-g-za Sep 26 '17 at 15:13
  • It presents no options. – Startec Sep 28 '17 at 2:12
  • i've added a screenshot of the config i see - is yours anything like that? do you have any custom settings for VNC, either on the pi or locally? Which model of raspberry pi are you running this on? – andrew-g-za Sep 28 '17 at 21:03

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