You could temporarily reset the network connection to use a static address, and remove any DNS entries in the NAS setup. Then it shouldn't be able to reach the VPN traversal servers.
I will have to try that. I have 4 seperate NAS devices saving to my local nas.
Each device is setup with a static IP.
I will need to log into each device to break the connection.
This has been happening daily here recently.
This will require a little time each day to do.
I would change ip's to stop the transfer and then I would need to change them back at the end of day so it will try and work again for the evening transfer.
I would prefer the "cancel" button to work as it should.
Otherwise there is no real way to stop the transfer without extra work.
I had to just shut down the backup this morning so tomorrow I may try this method.
Most home routers would let you block traffic for a specific device on schedule (part of parental controls). That's another possibility perhaps, you might check to see if your routers also support blocking rules on a schedule.
Maybe someone from Netgear will chime in on whether there's a more direct way to get the result you need.
