RHEL 7/8: portmap query failed: RPC: Remote system error - Connection refused

I've got a bit of a mystery on my hand. NFS was working fine for CentOS 6, but CentOS/RHEL 7 and 8 don't seem to work at all.
I suspect something has changed in NFS in those versions that I can't figure out.

I have tried forcing all to version 3, but that didn't help.

Server IP: 10.252.100.24 <-CentOS 7
Client IP: 10.252.12.73 <-RHEL8

Both can mount an identically setup CentOS 6 machine, but 6 can't mount 7 or 8.

Ok, here's what I've done.
Server (selinux,firewalld and iptables are diabled)
/etc/exports:
Code:/server 10.252.12.64/27(rw,sync,root_squash)hosts.allow:
Code:ALL: 10.252.12.64/255.255.255.224Client
Code:mount -vvv -t nfs server:/server /temp
mount.nfs: timeout set for Thu Sep 9 10:40:31 2021
mount.nfs: trying text-based options 'vers=4.1,addr=10.252.100.24,clientaddr=10.252.12.73'
mount.nfs: mount(2): Connection refused
mount.nfs: trying text-based options 'addr=10.252.100.24'
mount.nfs: prog 100003, trying vers=3, prot=6
mount.nfs: trying 10.51.197.24 prog 100003 vers 3 prot TCP port 2049
mount.nfs: portmap query failed: RPC: Remote system error - Connection refused
mount.nfs: trying text-based options 'vers=4.1,addr=10.252.100.24,clientaddr=10.252.12.73'
mount.nfs: mount(2): Connection refused
mount.nfs: trying text-based options 'addr=10.252.100.24'
mount.nfs: prog 100003, trying vers=3, prot=6
mount.nfs: trying 10.51.197.24 prog 100003 vers 3 prot TCP port 2049
mount.nfs: portmap query failed: RPC: Remote system error - Connection refused
mount.nfs: trying text-based options 'vers=4.1,addr=10.252.100.24,clientaddr=10.252.12.73'
mount.nfs: mount(2): Connection refused
mount.nfs: trying text-based options 'addr=10.252.100.24'
mount.nfs: prog 100003, trying vers=3, prot=6
mount.nfs: trying 10.51.197.24 prog 100003 vers 3 prot TCP port 2049
mount.nfs: portmap query failed: RPC: Remote system error - Connection refused
mount.nfs: trying text-based options 'vers=4.1,addr=10.252.100.24,clientaddr=10.252.12.73'
mount.nfs: mount(2): Connection refused
mount.nfs: trying text-based options 'addr=10.252.100.24'
mount.nfs: prog 100003, trying vers=3, prot=6
mount.nfs: trying 10.51.197.24 prog 100003 vers 3 prot TCP port 2049
mount.nfs: portmap query failed: RPC: Remote system error - Connection refusedTry forcing vers 3:
Code:mount -vvv -t nfs -o vers=3 server:/server /temp
mount.nfs: timeout set for Thu Sep 9 11:00:55 2021
mount.nfs: trying text-based options 'vers=3,addr=10.252.100.24'
mount.nfs: prog 100003, trying vers=3, prot=6
mount.nfs: trying 10.252.100.24 prog 100003 vers 3 prot TCP port 2049
mount.nfs: portmap query failed: RPC: Remote system error - Connection refused
showmount -e 10.252.100.24
Code:Export list for server:
/server 10.252.12.64/27
Ok, so I check RPC

rpcinfo -p 10.252.100.24
Code: program vers proto port service
100000 4 tcp 111 rpcbind
100000 3 tcp 111 rpcbind
100000 2 tcp 111 rpcbind
100000 4 udp 111 rpcbind
100000 3 udp 111 rpcbind
100000 2 udp 111 rpcbind
100003 3 tcp 2049 nfs
100003 4 tcp 2049 nfs
100227 3 tcp 2049 nfs_acl
100003 3 udp 2049 nfs
100003 4 udp 2049 nfs
100227 3 udp 2049 nfs_acl
100021 1 udp 51314 nlockmgr
100021 3 udp 51314 nlockmgr
100021 4 udp 51314 nlockmgr
100021 1 tcp 42148 nlockmgr
100021 3 tcp 42148 nlockmgr
100021 4 tcp 42148 nlockmgr
100007 2 udp 918 ypbind
100007 1 udp 918 ypbind
100007 2 tcp 921 ypbind
100007 1 tcp 921 ypbind
100005 1 udp 635 mountd
100005 1 tcp 53022 mountd
100005 2 udp 635 mountd
100005 2 tcp 57464 mountd
100005 3 udp 635 mountd
100005 3 tcp 38079 mountd
100024 1 udp 52274 status
100024 1 tcp 59019 statusSo NFS is open on 2049 and rpcbind on 111
telnet 10.252.100.24 111
Code:Trying 10.252.100.24...
Connected to server.
Escape character is '^]'.

telnet 10.252.100.24 2049
Code:Trying 10.252.100.24...
telnet: connect to address 10.252.100.24: Connection refusedOk, that's odd...

nmap 10.252.100.24
Code:Starting Nmap 6.40 ( http://nmap.org ) at 2021-09-09 10:52 EDT
Nmap scan report for recons (10.252.100.24)
Host is up (0.0018s latency).
rDNS record for 10.252.100.24: server.mydomain.com
Not shown: 997 closed ports
PORT STATE SERVICE
22/tcp open ssh
111/tcp open rpcbind
6000/tcp open X11What am I missing? Why is port 2048 refusing connection?