Niyaz1
No guarantee that I can help here - status 24 is one the most difficult errors to troubleshoot, simply because the issue is outside of NBU at the network level.
I have bookmarked this explanation of status codes 23/24/25 : https://vox.veritas.com/t5/NetBackup/Error-23/m-p/738836#M201891
It is possible to map the NAS storage to the media server and back it up from there (using same UNC path)?
In other words, use the media server as Client in the policy.
This will eliminate one network hop.
Another way to backup will be via NDMP protocol, using NDMP policy type. That is, if you have NBU licensing that allows NDMP.
For troubleshooting, you can create logs to get an idea of more or less where the break in comms is.
On the client, bpbkar log at level 3.
bpbkar will log every filename that is read and sent to the media server.
This will tell us up to where the client was able to read from the NAS and comms were good with media server.
On the media server: bptm and bpbrm logs at level 3.
bpbrm will log comms with client, metadata received from the client and comms with master server bpdbm to update metadata.
bptm will log each data buffer received from the client and write actions to the storage.
So, these 3 logs will give you an idea of where the break in comms is.
You can also ask your network team to monitor comms between filer -> client -> media server -> storage
during backup window.