I'm observing the same problem described by @hive, the 2 eth adapters are named as:
enp1s0
eth0 or eth1, meaning that the second adapter switch the name between eth0 and eth1 every time the nanopi-R4s reboot for instance after a kernel upgrade, creating a bunch of issues with the nat rules, vnstat and other tools that are configured with the name of that adapter.
The second problem is that the ethx (0 or 1) very often is losing its ip address and I must run the dhclient manually to get an ip address again, this adapter is connected directly to the Comcast modem.
Here the armbianmonitor -u link https://paste.armbian.com/ugewezical
Fernando Rivasplata got a reaction from poddmo in [Invalid] - Network ports inconsistent behavior with 21.02.1 on a NanoPi R4S 4GB