Was: ``` sysctl net.ipv4.ip_forward=0 ``` Set to: ``` sysctl net.ipv4.ip_forward=0 ``` Strangely enough, IPv6 is fine. ``` net.ipv6.conf.all.forwarding = 1 ``` Decision to forward is fully based on firewalld's config. @maxwschm found the fix for this. Thank you Maxwell.