Dual Boot Win 11 and Linux Mint 21.2... some problems

Hi there, I just received my LattePanda Sigma a few days  ago. 
 

1)  I immediately booted it up, and it took a few starts, plug pulling etc to get the HDMI video to work. It still does that. It doesn't matter what OS, it always does this.
 

This is before O/S selection. And happens on both O/S's........ just every time I start this PC up, I get no picture/video. I do get what looks like an analogue noisy white-ish (snowy) screen. (it has little 'pin-pricks' of colour on the mainly white screen)
 

When in Win 11, with video working, everything else seems to work; but.......
 

2) I have dual booted this PC with Linux Mint 21.2 Beta ....... the official release is due anytime from now onwards. (Later today, maybe tomorrow or next week? It hasn't happened yet... but it is imminent.)

The problems with the Dual Boot System are:
 

3) Wired Network Connection Problem: Normally as soon as I turn on my Linux Mint installations, the wired network connects automatically, and quickly, as I turn the PC on. But on this PC with Win 11 and Linux Mint installed, the Network does not connect quickly when using Linux Mint. More cable pulling, powering down, removing the PSU and reconnecting...... then it sometimes connects. (On windows this is not happening, it works fine)

4) No Sound at all when Linux Mint is selected. Unable to find the cause. Using ALSAMIXER I checked volume levels and mute settings, and they should work. Sound works well in Windows.
 

5) Some problems maybe caused from switching from Windows to Linux, as some Windows settings are saved, and applied at next boot... even if you have selected Linux !!! This has been mentioned a lot on Linux dual boot forums as something to be aware of, during fault finding. Unfortunately I am not a software faultfinder... I am new to this.
 

I am hoping that you can come up with solutions/patches, or even better develop a Linux Mint edition of your software for Mint users who have LattePanda Sigmas. Linux Mint has many users and is based on Ubuntu. So Ubuntu fixes should work on Mint...
 

If you need the results of any linux terminal command, I am happy to assist, or try out any suggestions and report back.

One other thing, your 'tech support' email address on your website (techsupport@lattepanda.com) does not work.
 

Thanks

Peter