WOL was working great on Bionic until yesterday's kernel update. How to diagnose/recover it?
Edit: if set to boot from 4.15.0-23 kernel it works. If set to boot from 4.15.0-24 it does not.
Edit2: WoL can be enabled with
sudo ethtool -s [card] wol g
but it isn't persistent. Searching for how to set it every boot.
Edit3: Per a comment by Kai-Heng Feng on this bug report this was an advertent change! (and therefore not a bug)
This is because the fix of LP: #1752772 has one commit  that disables WoL by default. Set WoL explicitly should solve your issue.  https://github.com/torvalds/linux/commit/7edf6d314cd061e1d0a1b7bc0b511d64322c3f72