Sys-net ethernet devices come up with a differnt name on each boot

So I thought by having a persistent (non-disposable) sys-net I would not have to configure the networking each time I booted (i need multiple static ip addresses). Unfortunately, it seems that when the system boots, it’s random what ethernet port gets called ens6f0, and what ethernet port gets called ens7f0, etc…

Any thoughts on how to resolve this?

In the Network-Manager settings, either for ethernet or wifi,
if you let your mouse on the device field, you got this tooltip:

This option locks this connection to the network device specified either by its interface name or permanent MAC or both. Examples: “em1”, “3C:97:0E:42:1A:19”, “em1 (3C:97:0E:42:1A:19)”

Instead of ens6f0 or ens7f0, use the MAC address only.
(if you let the device field empty, this should works too).