Wish I had known this before! My ageing NAS failed recently and doesn't seem inclined ever to run again. Thankfully all the important stuff on it was also on BT Cloud so not a total disaster. Rather than stump up for another NAS I thought I'd take a good look at what could be done with just a spare 1TB drive I had previously bought for no obvious reason other than being cheap. To my great surprise, just by connecting it directly to the Smart Hub 2 and adding its network location to each box on my LAN (\\192.168.1.254\usb1) the SH2 gets a chance to really show off its file server capabilities and all the LAN computers are able to use it without restriction. Initially I had tried connecting to it using mapped network drive letters but that wasn't really successful but adding its network location to each computer solved all the problems. The computers are all even booting noticeably more quickly so seems the old NAS was having connection problems. Nothing like that with a USB disk.
I have an ASUS router and BT fibre 900. I have a USB drive configured as a samba connected and managed by the router. I followed these instructions. It seems to work great. I have been using it for months as a NAS plus use the content to feed a plex server.
Samba 1 and 2 isn't encrypted although 3 can be. My home network is not exposed to the WAN so my Samba drive is only accessible on the LAN and folders are only accessible with password and usernames.