Nextcloud server loson connection to SMB server (ping included) after doing Save as in office

Ive setup a nextcloud server which is working fine

ive connected to a SMB share which is also fine

I can open files on my SMB share, i can drag and drop files and i can edit files using the inbuild nextcloud office app.

I have a problem where if open a document and goto save as… it immediately blocks network access between the nextcloud server and the smb server - if i ping from the windows server i get general failure, and if i ping from the nextcloud server i get no reply.

When its in this state, all other servers on the network are still able to ping the nextcloud server and the nextcloud server can ping them.

After 20 minutes or so the connection seems to be restored and is fine until i click save as again.

Anyone else seem similar behaviour?