Created attachment 224352 [details]
pciconf for the network card
We had some problems with repeated messages of:
Apr 21 13:36:12 is129 kernel: re0: watchdog timeout
Apr 21 13:36:12 is129 kernel: re0: link state changed to DOWN
Apr 21 13:36:16 is129 kernel: re0: link state changed to UP
coming up once or twice a minute.
This machine is a router with two out of four network interfaces active. No more traffic was able to pass the router at that time.
We had similar problem (no more traffic passing the router) three times before with several weeks working fine in between. The logs don't show this watchdog timeout / link DOWN at those times.
A reboot always resolved the problem.
See also: bug #166724