nvidia – Ubuntu 20.04 Second monitor is not working

I tried to connect my laptop with the second monitor, however, it displays on the second monitor that No HDMI signal from your device. When I checked the Displays setting, there is no monitor too.
I use ASUS Gaming. This is the configuration of Ubuntu 20.04
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When I checked xrandr in the terminal:
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I also updated to the kernel 5.6 but nothing changes
Here is the setting of the software updates, there are no additional drives
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I hope anyone can help me because I need to work on a big screen.
Thanks in advance.