with both of my omv installations (4 and experimentally 5, see details below) I had the same irritation: The enpXs0 network interfaces (my board has two of them), enp1S0 and enp2S0 by intallation, after some time suddenly changed to enp2s0 and enp3s0. In both cases, omv came up with no accessible network address no more, and I needed to connect monitor and keyboard again to fix it via omv-firstaid.
I wonder, if someone out there can tell me, why this happens.
Could it be because of the BMC included in the Aspeed ATS2300 chip on the Asus P9D-I, btw a really nice feature of this board? But if, why does it not come up from the start, but somewhen later after a reboot or a shutdown? And why does it keep omv or debian from defaulting to DHCP and rather leaves system with no active network interface at all?
I just like to understand.