I found a post here which explains which services you need to allow through the firewall in order for vagrant to work.
Example for easily configuring firewalld using the “firewall-config” GUI:
choose "Configuration: Permanent" from the drop down menu
select the zone you want to modify (i chose "internal").
go to the "Interfaces" tab, assign vboxnet0 (or other host-only adapter) to the zone.
go to the "Services" tab, check "mountd", "nfs" and "rpc-bind"
go to the global "Services" tab (next to "Zones"), select NFS and add Port 2049 UDP (only TCP is predefined).
Finally choose "Options/Reload Firewalld".
NFS mounts now work correctly from within the VM and you can leave firewalld enabled.
I had trouble with SELinux which I resolved by deleting the .old files in /etc/firewalld/zones
I managed to get “vagrant up” working and “vagrant ssh” to get in. I got discourse up and running.