Client is Ubuntu Xenial, manually mounting works just fine:
mount 10.0.0.12:/mnt/d1 /mnt/d1
I then copy that line from /etc/mtab to /etc/fstab:
10.0.0.12:/mnt/d1 /mnt/d1 nfs4 user,rw,relatime,vers=4.0,rsize=1048576,wsize=1048576,namlen=255,hard,proto=tcp,port=0,timeo=600,retrans=2,sec=sys,clientaddr=10.0.0.23,local_lock=none,addr=10.0.0.12 0 0
umount /mnt/d1
and then mount it again using fstab:
mount /mnt/d1
and it times out at that time.
The nfs server is centos7
Updated firewalld:
firewall-cmd --permanent --zone=public --add-service=nfs
and reloaded, with /etc/exports like so:
/mnt/d1 10.0.0.0/24(rw,sync,no_subtree_check)