All of a sudden, NFS sharing is busted. Getting 'mount(2) No such file or directory error

When I was running Debian 10.3, this setup worked perfectly. After updating to 10.4 a few weeks ago, my NFS server has been busted. Been trying to fix it for a while and finally threw in the towel and decided to ask for help. :(

Here we go.....

/etc/exports from Server-PC: (server IP is 192.168.1.5)

Code:/mnt/md0/data 192.168.1.1/24(ro,insecure,sync,all_squash,nohide,no_subtree_check,anonuid=1000,anongid=1000)Server is up and running:

Code:service nfs-kernel-server status
nfs-server.service - NFS server and services
Loaded: loaded (/lib/systemd/system/nfs-server.service; enabled; vendor preset: enabled)
Active: active (exited) since Sat 2020-08-22 16:03:51 EDT; 14min ago
Process: 20803 ExecStartPre=/bin/sleep 15 (code=exited, status=0/SUCCESS)
Process: 20808 ExecStartPre=/usr/sbin/exportfs -r (code=exited, status=0/SUCCESS)
Process: 20809 ExecStart=/usr/sbin/rpc.nfsd $RPCNFSDARGS (code=exited, status=0/SUCCESS)
Main PID: 20809 (code=exited, status=0/SUCCESS)

Aug 22 16:03:36 server-pc systemd[1]: Starting NFS server and services...
Aug 22 16:03:51 server-pc systemd[1]: Started NFS server and services.No restrictions in hosts.allow or hosts.deny

When doing exportfs:

Code:sudo exportfs
/mnt/md0/data 192.168.1.1/24Code:sudo cat /proc/fs/nfsd/versions
-2 +3 +4 +4.1 +4.2And from the client (which has IP address 192.168.1.253)... fstab

Code:192.168.1.5:/md0/data /mnt/data nfs ro,sync,hard,intr,noexec 0 0
Code:sudo /sbin/showmount -e 192.168.1.5
Export list for 192.168.1.5:
/mnt/md0/data 192.168.1.1/24But when trying to mount the NFS share:

Code:sudo mount -a -vvvv
/ : ignored
/media/cdrom0 : ignored
mount.nfs: timeout set for Sat Aug 22 16:24:38 2020
mount.nfs: trying text-based options 'hard,intr,vers=4.2,addr=192.168.1.5,clientaddr=192.168.1.253'
mount.nfs: mount(2): No such file or directory
mount.nfs: trying text-based options 'hard,intr,addr=192.168.1.5'
mount.nfs: prog 100003, trying vers=3, prot=6
mount.nfs: trying 192.168.1.5 prog 100003 vers 3 prot TCP port 2049
mount.nfs: prog 100005, trying vers=3, prot=17
mount.nfs: trying 192.168.1.5 prog 100005 vers 3 prot UDP port 36049
mount.nfs: mount(2): Permission denied
mount.nfs: access denied by server while mounting 192.168.1.5:/md0/dataGuessing something changed with some Debian update recently and this is what broke it since the NFS setup was humming along perfectly for several months until recently.

No firewall or security software installed on either machine. Absolutely nothing has changed except for Debian updates being applied once every few weeks.