Enable HDMI after boot on Raspberry Pi4

I have been running a Pi4B successfully for some time. During testing I had a HDMI monitor attached. How ever I have noticed that the monitor has to be attached at boot time for it to work. If I boot and then attach the monitor nothing is displayed. I have searched but cannot find any command that will enable the monitor after boot.

is there any way to start the display/
TIA

common issue... alot of threads on the rpi forum..., afaik there is a 'force-on' parameter for config.txt for this... (or similar)

Thanks a lot for that. I didn't think to look for raspberry pi issues. I was always adding "openwrt" to the search terms.
As you say, there are many threads on this.
Unfortunately none seem to work. I suspect that the TV I am using is the problem

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on raspberry, the hardware configuration is done with text files in boot folder and is the same for all operating systems, OpenWrt, Raspberry OS or Debian or anything else.

I have solved the issue. For those interested the solution I required is to add the following lines to config.txt

hdmi_force_hotplug:0=1
hdmi_group:0=2
hdmi_mode:0=39
hdmi_force_hotplug:1=1
hdmi_group:1=2
hdmi_mode:1=39

Most of the information on the web only refers to hdmi_force_hotplug which has been deprecated to the new form hdmi_force_hotplug:0 to refer to HDMI0 and hdmi_force_hotplug:1 to refer to HDMI1

I had to add the remaining lines for my monitor which is 1360x768 because the pi did not automatically detect resolution.

Thanks for the assistance

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thankyou for coming back with your findings... those options are new/s to me...

good to know...

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