External Monitor Will Not Connect | Ubuntu 20.04.3

I'm having issues connecting my external monitors to my laptop. I'm using Ubuntu 20.04.3. Any thoughts? I looked this problem up and it looks like something may be broken in my packages...

sudo ubuntu-drivers autoinstall
[sudo] password for harry: 
WARNING:root:_pkg_get_support nvidia-driver-390: package has invalid Support Legacyheader, cannot determine support level
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 nvidia-driver-510 : Depends: libnvidia-gl-510 (= 510.47.03-0ubuntu0.20.04.1) but it is not going to be installed
                     Depends: libnvidia-extra-510 (= 510.47.03-0ubuntu0.20.04.1) but it is not going to be installed
                     Depends: libnvidia-decode-510 (= 510.47.03-0ubuntu0.20.04.1) but it is not going to be installed
                     Depends: libnvidia-encode-510 (= 510.47.03-0ubuntu0.20.04.1) but it is not going to be installed
                     Depends: xserver-xorg-video-nvidia-510 (= 510.47.03-0ubuntu0.20.04.1) but it is not going to be installed
                     Depends: libnvidia-cfg1-510 (= 510.47.03-0ubuntu0.20.04.1) but it is not going to be installed
                     Depends: libnvidia-fbc1-510 (= 510.47.03-0ubuntu0.20.04.1) but it is not going to be installed
                     Recommends: libnvidia-compute-510:i386 (= 510.47.03-0ubuntu0.20.04.1)
                     Recommends: libnvidia-decode-510:i386 (= 510.47.03-0ubuntu0.20.04.1)
                     Recommends: libnvidia-encode-510:i386 (= 510.47.03-0ubuntu0.20.04.1)
                     Recommends: libnvidia-fbc1-510:i386 (= 510.47.03-0ubuntu0.20.04.1)
                     Recommends: libnvidia-gl-510:i386 (= 510.47.03-0ubuntu0.20.04.1)
E: Unable to correct problems, you have held broken packages.

Thanks in advance for all your help!

I had the same issue - I was surprised it didnt give more info other then listing the dependency packages. I started trying to sudo apt install the dependency packages hoping they would give more information.

1. I tried sudo apt install libnvidia-gl-510
2. that told me unmet dependency on libnvidia-common-510
3. so i didnt sudo apt install libnvidia-common-510
4. that installed itself and a bunch of other nvidia packages.
5. rebooted
6. hdmi worked!