Started to wright this a day or so ago.
Hi there.
I have the same tuner as you in fact I run two of them and they have been for the most part rock solid for a couple of years now. I can confirm that they are dual DVB-T2 tuners as well as DVB-C.
Now I have only had a skim though this thread so i will have missed things all ready covered by others. Things such as Ubuntu asking for install media when installing packages. That's generally down to at point of install skipping the Ubuntu repo setup. Not seen the option when installing the desktop version of Ubuntu. In my experience this is only ever an option to skip when using Ubuntu Server install media which is my preferred option. I run headless and use either Webmin, cockpit or ssh to access and administer.
Also just a word of warning re snaps from an old school fart..... DON'T USE THAT S@!T.
Yes I know you can't really fully avoid all snaps any more but I have had endless head aces with snaps and trying to get software that requires access to hardware such as USB devices or even DVD-ROM's due to permissions. Now that's going to be down to me and not wanting to learn how to administer snaps from the command line but if your confident with them and their permissions then go for it.
For me it adds another layer of nu-nessiceryness. Especially for a TV server running in my home environment, JUST NO NEED. I can see there benefit but there just not for me.
Now I see your newish to Linux, welcome to the side of light lol. I read some where you said about some of the Linux commands being the same as DOS/CMD/Powerscript (whatever). If any thing Windows commands have become more Linux like such as using tab to cycle though previous commands (was in Linux first) and since Windows 10 (I think) you can now ssh strait from CMD rather than installing putty. Also if you think TVHeaend is hard try MythTV. Any how I digress.
I'm not much good at fault finding and I generally re-install when I hit a problem I can't get around which is something I have never been able to shake from my days as a Windows user but I thought that sharing my install run though might help you in some way so here goes.
First stick with Ubuntu 20.04LTS desktop if your that new to linux unless you know how to use ssh, then by all means go with server version to save resources. I have had a few issues with HD EPG which I have now un-wittingly fixed by using 20.04 over 22.04. That said I will be trying 22.04 again soon with HWE kernel as that was my fix over generic kernel but for now I know 20.04 works.
Referance
https://releases.ubuntu.com/focal/
I'm going to assume your ok with installing the dekstop after all if you can install windows you can install ubuntu. My only suggestion is that you go for the minimal install which is an option you will be presented with. Of course provided that this machine is only for serving TV.
So once you have it installed and your logged in first thing to do is change a few settings which you can do though the GUI. Either top right menu or Windows key then type settings.
Set your self a static ivp4 (ivp6 another thing I can't be assed to learn) ip, subnet, dns and gateway. Then go to power settings and disable any standby hyphenation as this is a machine you want to serve TV to your network and don't want it to fall a sleep.
We then open the termainal by either "ctl+alt+t" or "windows key" then type terminal hit enter.
Now copy paste one after the other
sudo apt update
sudo apt upgrade
type y hit enter when asked
Once done
sudo reboot
repeat this process again and again until "All packages are up-to-date." message is shown.
We now want to change to the HWE kernel as thus far it just works compared to generic which in my experience only kinda works.
Interestingly my little VM that I'm testing with to wright this preinstalled with HWE kernel so you might not need to do this. It will either install or just tell you
"linux-generic-hwe-20.04 is already the newest version (5.15.0.78.85~20.04.38)" In which case grate, move on.
Referance
https://askubuntu.com/questions/1314328/ubuntu-20-04-how-can-i-enable-hwe
sudo apt install linux-generic-hwe-20.04
sudo reboot
Optional
sudo apt autoremove
This will remove the no longer needed generic kernel and any other software packages no longer needed due to updates.
In my little test install VM there was nothing to remove, again move on.
Now we install the hauppage PPA
Referance
https://hauppauge.com/pages/support/support_linux.html
sudo add-apt-repository ppa:b-rad/kernel+mediatree+hauppauge
sudo apt update
sudo apt install linux-hwe-mediatree linux-firmware-hauppauge
sudo reboot
Now install the TVHeadend PPA/Repo
First make sure curl is installed as it was not in my VM.
sudo apt install curl
then copy and paste as one
curl -1sLf \
'
https://dl.cloudsmith.io/public/tvheadend/tvheadend/setup.deb.sh' \
| sudo -E bash
Then
sudo apt update
sudo apt upgrade
sudo apt install tvheadend
sudo reboot
You should now hopefully have a working install ready to setup from a web browser either locally or on another machine connected to your network
ip:9981
e.g 192.168.1.50:9918
Good luck I hope this helps and that I've not missed the point of your issue completely by not reading every thing.