I encounter the same symptoms as reported over in the following Ubuntu
Bugtracker entry, my sky2 ethernet card does not work after resuming from sleep
(S3). I use a custom compiled Kernel (tested with 5.2.2 and 5.3-RC1) from the
Suse Github sources:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1798921

By the way, in my custom config I didn't use the module version but compiled in
the sky2 driver. Hence a "modprobe -r sky2; modprobe -i sky2" (which was
mentioned as a workaround) results in a "modprobe: FATAL: Module sky2 is
builtin."

It was reported that adding "pci=nomsi,noaer" as Kernel parameters could
workaround the issue, but I haven't tested it yet myself. This could have
negative performance implications though and hope this can be fixed finally
upstream in a less invasive way.