NFS - broken recent update - odroid C2 (+maybe more?)

[networkfailserverx]

i had a working NFSv4 config for a few months. then in the past couple months, without changing any configs except installing an update, it has been impossible to avoid an error which states only 'no such file or directory' when trying to mount an NFS share.

i have since wiped the OS and setup NFS from scratch (including v3) with the minimal changes possible from a default install, but the exact same error persists. so it can't be something i have changed.

as a test, i have also successfully setup NFS a couple times with identical configuration files (the default nfs-server.service systemd file, an empty iptables, minimal adjustments to the commented example lines in /etc/exports) on a common x86 distro, and "mount -vv 127.0.0.1:/ /mnt" worked without issue.

i have checked many times that the file or directory does exist, set permissions to nobody:nogroup, fiddled with /etc/exports file, etc. but the update must've broken something. i'm unsure if the problem lies with nfs-utils or the odroid-c2 kernel, but i have updated the kernel numerous times without any nfs issues. so it could potentially be the august update to nfs-utils https://archlinuxarm.org/packages/aarch64/nfs-utils

have done numerous web searches but it is not an error with a single solution. it is also unclear how to debug it or where to look for error messages

could someone test nfs-utils on their own setup to confirm? you only need to install nfs-utils, setup a simple /etc/exports, start the nfs server, and attempt to mount it to loopback, then check if it worked:
$this->bbcode_second_pass_code('', 'pacman -S nfs-utils
mkdir /srv/nfs4 /mnt/test
touch /srv/nfs4/touch-file
chown -R nobody:nogroup /srv/nfsv4
echo "/srv/nfs4 *(rw,sync,fsid=0,no_subtree_check,all_squash)" | tee -a /etc/exports
systemctl restart nfs-server
mount.nfs4 -vv 127.0.0.1:/ /mnt/test
mount | tail -1
ls /mnt/test
')
the above should work as sudo or root, but you may need to open your firewall (or at least the loopback)

if it is working on your board perhaps it is only the odroid-c2 that is affected.

would happily donate to archlinuxarm for a fix!