Hello luciano and thanks for the hints.
The NAS device is in the same network but in different switches.
I solved the issue by applying again the network config via nmcli and deleting the route below:
192.168.1.0/24 dev eno1 proto kernel scope link src 192.168.1.39 metric 100
[user@host ~]$ route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.1.1 0.0.0.0 UG 100 0 0 eno1
192.168.1.0 0.0.0.0 255.255.255.0 U 100 0 0 eno1
Maybe I set the duplicate route by mistake after applying static IP address via UI, I had some issues and then I disabled the network manager and I set it up by editing the /etc/sysconfig/network-scripts/ifcfg-eno1
Removing the kernel route, the ping now is direct and stable and the NFS share is working like a charm:
[user@host ~]$ ping 192.168.1.40
PING 192.168.1.40 (192.168.1.40) 56(84) bytes of data.
64 bytes from 192.168.1.40: icmp_seq=1 ttl=64 time=1.16 ms
64 bytes from 192.168.1.40: icmp_seq=2 ttl=64 time=0.694 ms
64 bytes from 192.168.1.40: icmp_seq=3 ttl=64 time=0.895 ms
Thanks again for your support.
Have a nice day!