EM7455, Ubuntu 20.04 (server) -- "primary port" changes from one boot to the next

I have some OnLogic PCs with the “NWK200” modules (EM7455).
I am able to configure and communicate with these modules (with Verizon).

Unfortunately, on at least one of these machines, the “primary port” name changes sometimes after a reboot. EG, it might be cdc-wdm2 for awhile, then maybe come up as cdc-wdm1. This is making it difficult to stay connected between start-ups. OnLogic support says they can’t help and I should look into udev rules because having multiple USB devices come up in different orders may cause this.

I created a rule to find the device using idVendor and idProduct and create a symlink. But when I use “nmcli r wwan on” it reports an error about inconsistent device names.

I’m not the most skilled with udev rules but I suspect it might not help as the device name is set before the rules fire (?).

I’ve tried both the native Ubuntu 20.04 qmi-wwan/qcserial drivers and the GobiNet/GobiSerial drivers with the native drivers black-listed, with the same result.

For a workaround, I have added multiple connections with nmcli hoping one device will connect, and this seems to work but I don’t feel it’s a valid solution. eg:

sudo nmcli c add type gsm ifname cdc-wdm1 con-name vzw1 apn vzwinternet
sudo nmcli c modify vzw1 connection.autoconnect yes

sudo nmcli c add type gsm ifname cdc-wdm2 con-name vzw2 apn vzwinternet
sudo nmcli c modify vzw2 connection.autoconnect yes

So – is there a way I can enforce that the device name is the same always?

Lacking a reply for how to symlink or set the cdc-wdm* name, here’s what I ended up doing… I’d searched the web many times trying to find a clue; it turns out Ubuntu 20.04 NetworkManager will happily add a gsm device WITHOUT the cdc-wdm* name and appears to always find it, even when the kernel-supplied name comes up differently from one boot to the next.

To whit, just:

sudo nmcli c add type gsm con-name vzw1 apn vzwinternet