Now I was forced to try upgrading to Caddy 0.9.3 as my sites stopped working for some reason.
I still got the capabilities error, but it was solved with this: Caddy won't start, strace shows it's waiting for a mutex of some sort - #11 by coderobe
“Commenting out CapabilityBoundingSet AmbientCapabilitiesandNoNewPrivileges in the systemd unit file”
I will open a new topic for inability to renew certs.