It could be a lot of reason why, but from what ports you have shown me I did not see the NFS ports.

I. Please enter this command from client side:
1. rpcinfo -p IP_of_nfsserver
You should see a list that contain: portmapper, nfs, mountd, nlockmgr, status

2. showmount -e IP_of_nfsserver
You should see a list of NFS shares

II. Check if your ip address has sufficient right to enter chosen share

III. If above commands give a positive output, please use this mount options:
mount -t nfs -o tcp, rsize=1500, wsize=1500 IP_of_nfsserver:/share/SHARE_NAME

IV. It could be a firewall on client side, for check it out, please turn off firewall.