Bottom Line: SMB Was Healthy; the Local PC Was Taking the Wrong Tailscale Route
The transfer stalled, ZimaOS Files also threw network errors, and Windows eventually reported 0x8007003B. The decisive test was turning off Tailscale on the local Windows PC. SMB immediately behaved normally. The NAS was not fixed by changing disks or restarting Samba; the path to the NAS changed.
Why a Local Connection Can Accidentally Leave the LAN
The home router was also a Tailscale subnet router advertising the entire 192.168.8.0/24 network. A local Windows PC running Tailscale could therefore have both a directly connected route and a Tailscale route toward the same LAN. The thread described this as NAT hairpinning, but the more general and useful diagnosis is route overlap/asymmetry.
Tailscale's current overlapping subnet routes explains that Windows and macOS accept subnet routes by default and that overlapping routes can require deliberate route design.
Prove the Route Before Touching SMB Settings
route print
tracert ZIMAOS_LAN_IP
tailscale status
ping ZIMAOS_LAN_IPRun the test once with Tailscale enabled and once disabled. If SMB only fails when the overlay network is active, keep the storage/share configuration unchanged and fix the network path. This avoids wasting time on permissions, filesystems and Samba tuning.
Use the ZimaOS LAN Address When You Are Already at Home
On the local network, connect to the NAS by its LAN IP or local hostname. Use Tailscale when you are remote. If you deliberately advertise the home LAN through a subnet router, make sure your tailnet route policy does not pull normal same-LAN traffic into an unnecessary route.
The ZimaOS SMB authentication is the control path for file-sharing configuration.
What Error 0x8007003B Does and Does Not Tell You
Windows labels it an unexpected network error. It does not identify a disk failure, SMB credential problem or router problem by itself. Microsoft network errors are symptoms; the route test is what localizes this case.
Microsoft's Windows SMB behavior provides the protocol context.
ZimaClient and Tailscale Can Also Compete for Network Paths
The same thread found that running both client approaches on the same Windows machine could produce confusing behavior in that environment. Current ZimaOS supports either built-in ZimaClient remote access or standard-protocol Tailscale/WireGuard paths. You do not need both active for the same job.
The ZimaClient remote access and Tailscale remote access let you choose one model intentionally.
A Safer Home-Lab Routing Pattern
Keep local LAN access direct. Advertise only subnets that truly need remote reachability, and avoid overly broad routes when narrower ones would work. If the subnet router is also your main router, document which device owns NAT, DHCP, Tailscale routing and default-gateway behavior. Complexity at the network edge often appears as “SMB randomly hangs” higher up the stack.
One final control is to copy the same test file to the same SMB share from a second LAN computer that is not running Tailscale. If that transfer remains stable, you have a clean A/B comparison that points back to the affected client's routing state rather than server-side storage performance.
FAQ
Why does SMB work when I disable Tailscale?
That strongly suggests a route or overlay-network interaction rather than a ZimaOS disk or SMB-service failure.
Is Windows error 0x8007003B a Samba bug?
Not necessarily. It is a generic network-transfer error and can be caused by route instability, filtering, VPN software or other network-path problems.
Should I disable subnet routes completely?
Only if you do not need them. A better design is to advertise only the networks needed remotely and avoid conflicts with directly connected LAN routes.
Can I use Tailscale for SMB when away from home?
Yes. A Tailscale address or advertised home subnet can carry SMB remotely when routing and access controls are configured correctly.
Do I need both ZimaClient and Tailscale?
No. They are different remote-access approaches. Running both is optional and can add routing complexity on some clients.
