Accessing files in mounted NFS share hangs

I am creating a NFS share. I've configured the NFS server and also the NFS client.

My share was working perfectly fine until yesterday and now I found out it doesn't work.

I redid all the steps of NFS configuration and it still doesn't work.

My problem is that when I try to access my mount folder using cat /mnt/nfs1.txt (which was working perfectly fine until yesterday), nothing appears on the screen. And it looks like it is hanged or it collapsed.

root@ela-native:~# cat /mnt/nfs1.txt 

After this nothing appears on the screen and also I have to close the terminal to quit.

What am I doing wrong?

Edit1

The following are the steps in my configurations for the nfs:

NFS server:

sudo apt-get install nfs-kernel-server sudo mkdir /var/nfs/general sudo nano /etc/exports /var/nfs/general *(rw,sync,no_root_squash,no_subtree_check) sudo exportfs -a sudo service nfs-kernel-server start 

NFS client:

sudo apt-get install nfs-common sudo mount 172.21.215.101:/var/nfs/general /mnt 

And also if i run mount -t nfs, i get this:

root@ela-native:/home/salini# mount -t nfs 172.21.215.101:/var/nfs/general on /mnt type nfs (rw,vers=4,addr=172.21.215.101,clientaddr=192.168.164.78) 

I also tried showmount -e 172.21.215.101 i got

clnt_create: RPC: Port mapper failure - Timed out 

Edit2

And the i tried less /var/log/boot.log in the server machine and according to my understanding, i think that there is some error with the nfs server.

[ESC[0;1;31mFAILEDESC[0m] Failed to start Automatically refresh installed snaps. [ESC[0;1;31mFAILEDESC[0m] Failed to mount /mnt/nfs/var/nfs. See 'systemctl status mnt-nfs-var-nfs.mount' for details. [ESC[0;1;33mDEPENDESC[0m] Dependency failed for Remote File Systems. Starting Permit User Sessions... Starting LSB: VirtualBox Linux kernel module... Starting LSB: Set the CPU Frequency Scaling governor to "ondemand"... Starting LSB: Speech Dispatcher... Starting LSB: automatic crash report generation... Starting LSB: Apache2 web server... Starting LSB: daemon to balance interrupts for SMP systems... [ESC[0;32m OK ESC[0m] Mounted /mnt/nfs/home. 

What is the problem here?

Edit3

I did sudo ufw status numbered and sudo netstat -nlp | grep :111. I got this:

root@wsm-ela-inc6:/home/test# sudo ufw status numbered Status: active To Action From -- ------ ---- [ 1] 514/tcp ALLOW IN Anywhere [ 2] 514/udp ALLOW IN Anywhere [ 3] 514/tcp (v6) ALLOW IN Anywhere (v6) [ 4] 514/udp (v6) ALLOW IN Anywhere (v6) root@wsm-ela-inc6:/home/test# sudo netstat -nlp | grep :111 tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN 3062/rpcbind tcp6 0 0 :::111 :::* LISTEN 3062/rpcbind udp 0 0 0.0.0.0:111 0.0.0.0:* 3062/rpcbind udp6 0 0 :::111 :::* 3062/rpcbind 

Edit4

I did :

sudo ufw allow from 192.168.1.0/24 to any port 2049 sudo ufw allow from 192.168.1.0/24 to any port 111 

And I tried again for showmount but then again the terminal give me this

clnt_create: RPC: Port mapper failure - Timed out

Also I tried sudo service portmap restart and i got portmap: unrecognized service. Also i tried sudo service statd restart, it went well. Then again i tried showmount but still the same problem.

Edit5

I also tried netstat and got this:

 tcp 0 0 wsm-ela-inc6.csez:52630 maa03s29-in-f2.1e:https ESTABLISHED tcp 0 0 wsm-ela-inc6.csez.z:nfs wsm-ela-inc6.csez.z:890 ESTABLISHED tcp 0 0 wsm-ela-inc6.csez:34388 stackoverflow.com:https ESTABLISHED tcp 0 0 wsm-ela-inc6.csez:35504 maa05s06-in-f8.1e:https TIME_WAIT tcp 0 0 wsm-ela-inc6.csez.z:890 wsm-ela-inc6.csez.z:nfs ESTABLISHED tcp 0 0 wsm-ela-inc6.csez:39524 maa03s22-in-f2.1e:https TIME_WAIT tcp 0 0 wsm-ela-inc6.csez:shell 192.168.164.78:58982 ESTABLISHED tcp 0 0 wsm-ela-inc6.csez:34414 stackoverflow.com:https ESTABLISHED tcp 0 0 wsm-ela-inc6.csez:34438 stackoverflow.com:https ESTABLISHED