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.
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
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.
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.