Having to install things mostly through flatpaks works seamlessly until it doesn’t. Then you’re stuck in dependency hell where you have to open holes in your containers to allow access to files or binaries.
I’m at a point where I layer enough software that I don’t know If there is still value added.
First thing I’d do is to look at the client (fedora) journal for anything funky happening.
‘sudo systemctl status nfs-client’
Since it’s random I assume you won’t have any timeout in your /etc/fstab but it might be worth taking a look anyway.
Be aware that if the network drops the NFS will be disconnected and won’t auto-reconnect so this could also be the issue.
I don’t know if it plays well with container mounted volume, but looking at autofs could be a solution to auto-remount the share. I use it profusely for network mounted home directories.