On my Thinkpads over 20 years (T23, X200, T430s) it's been a non-issue.
Suspend powers down NIC from D3 running state to D0 suspended, dropping carrier.
Resume powers it back up from D3 to D0, restablishing carrier, marking it UP in ifconfig, otherwise unchanged.
Boot up once with verbose booting (I do so always), then detach then reattach the cable, logging for a comparison later.
Then suspend, pause and resume a time or two
. View /var/log/messages e.g. with less(). Save all that tail to a file.
You can see it with dmesg, but log timestamps are illustrative.
Explore, see what happened - and not just with the NIC/s.
I'm unsure if setting WoL with ifconfig can work to resume Thinkpads from suspend, if that's what's hoped for.
HTH