Windows 7 Sharing to arm based linux/Linux OS

So I have windows 7 "server" as file server for my RPI2 running OSMC(arm based linux)

Now after a while OSMC would lose access to shared files on my win7 file server, this is intermittent, sometimes it can have access for 1~30days, then suddenly anywhere in between win7 will stop severing arm based linux or Linux all together, such as any android phones as well. so its no the OSMC side just double confirm it win7 server as my machine will still be accesiable by any linux based os on the network fine.

Error message is pretty generic, no useful detail.

After restarting the file server everything resumes normal operation and devices can access those shares again.

I've tried messing around with SMB switch to different versions etc.. nothing has helped

Any ideas what causing this strange issue?