Why doesn't mount with nfs work?

Question

linux

Greetings gentlemen. There is a piece of bash script:

if ! grep ^$hzvzenter_SERVER_IP:/linuxcoe /proc/mounts 1>/dev/null 2>&1; then
            mkdir -p /linuxcoe-iso
            CMD_ERR=`mount -t nfs SERVER_IP:/linuxsys /linuxsys-iso`
            if [ "$?" != 0 ]; then
                CMD_ERR=`hzvzenter_format_error_msg $CMD_ERR`
                hzvzenter_post_event 0 "iso" 2 "hzvzenter-kvm-vm" "Could not mount ISO repository $hzvzenter_SERVER_IP:/linuxcoe! $CMD_ERR"
                exit 1
            fi
        fi

And I see in the logs the error "could not mount ..." I think this is because this command crashes on timeout:

mount -t nfs $hzvzenter_SERVER_IP:/linuxsys /linuxsys-iso

And this is true, if I execute a command as root, nothing happens. It just starts and that’s it, it doesn’t freeze, but it runs endlessly.
There seems to be a problem with NFS on the remote host. But nfs-kernel-server and nfs-common are both installed here and there. Why does it all not work and what needs to be done to make everything start? How to debug everything?
The bash script is part of a large open source system, the control panel via the web interface, it was partially changed, but it looks like the problem is not in changing the code, because no one specifically touched this piece, but everything crashes on this piece. How to debug this NFS?

Answer 1

first, see what is in /etc/exports on the server where you connect the
second mandatory thing is to look at the firewall settings on the servers

Answer 2

rpcbind check