M1 MBP, HDNative with Thunderbolt-PCI chassis

[Injured_Ear]

I upgraded from a 2012 Mac Pro Cheesegrater tower to a new M1 MacBook Pro and wanted to keep my UAD and HD Native PCI cards, so I bought the Echo iii Sonnet Thunderbolt3-PCI chassis.

I was having a repeated problem: Pro Tools (2021.12) would lose communication with the HD Native engine after approximately 30 minutes and would not re-establish until I had switched engines, restarted and switched back.

I thought it was related to OS Monterey (it was not)
I thought it was related to the HD Driver (it was not)

It took a lot of troubleshooting to get it all working smoothly and I just wanted to share with you all the solution, and a few caveats:
From the compatibility list on the Sonnet site:
https://www.sonnettech.com/support/d...patibility.pdf

Says it's compatible with HD Native PCI card, but look at the small print:
d: These cards have been discontinued, Continuing OS support may be limited (this was news to me!)
2. These cards draw more than 3 Amps at 3.3V, exceeding the specification for a single PCIe slot chassis (it's working, nothing has blown up yet)

Getting into the installation: I skipped over the instructions for Optional Step 8 and 9 in the card installation.
https://www.sonnettech.com/support/d...desktop_ug.pdf

For folks with HDX cards, it says to flip a switch inside the chassis.
Gen 3/Gen 2(HDX)

I did not flip that switch thinking since I did not have an HDX card, it does not apply to my situation. This was an incorrect assumption. Flip the switch!

Now all is running smoothly.