Why user is unable to access file on a nfs-share, despite having the required permissions?

Issue

• The user is having the required permissions; However, accessing the file results in permission denied:

  [user2@hostname ~] $ id
  uid=1200001230(user2) gid=185419(group2) groups=185419(group2),185058(group1)
  
  [user2@hostname ~] $ ls -l /home/drrepo/prod/Source_Files/IPX/tdw                                                                                                                                                                                                         
  -rwxrwx--- 1 user1 group1 5 Feb  5 11:28 /home/drrepo/prod/Source_Files/IPX/tdw
  
  [user2@hostname ~] $ cat /home/drrepo/prod/Source_Files/IPX/tdw                                                                                                                                                                                                          
  cat: /home/drrepo/prod/Source_Files/IPX/tdw: Permission denied
  

• Here, user2 is trying to open the file, which has 'rwx' access to users and groups.

• The file is owned by user1 and group1

• user2 is a member of group1.

• The file is in a NFS share, where the NFS server vendor is EMC Isilon.