Is Client1 a machine connected to the RUT955's LAN or is it also an independent ZeroTier node?
If Client1 is just a LAN client to RUT955 (which is a ZeroTier node), then you probably need to implement additional routing. For example:
- Add a static route to the ZeroTier network or just the Windows server in the Network → Routing → Static Routes page. For example:
- Set up port forwarding to Windows server's ZeroTier IP in the Network → Firewall → Port Forwarding page. Perhaps this reference will come in handy for this (it's for a newer device, but the principle remains the same).
If Client1 is already on the ZeroTier network as a node, it's most likely a firewall issue. However, without understanding the full context it's hard to predict where exactly.
A quick way to test whether the issue is with RUT955's firewall would be to add this line in the Network → Firewall → Custom Rules page or execute it as a command via SSH/CLI:
- iptables -I FORWARD -s <Client1_IP> -d <Server1_IP> -j ACCEPT
Or disable the firewall entirely with these commands:
- iptables --flush
- /etc/init.d/firewall stop
To enable it again:
- /etc/init.d/firewall restart
Some other things that could be causing this (although it's unlikely):
- ZeroTier LAN route was deleted in ZeroTier central?
- ZeroTier can also act as a firewall. Perhaps additional rules that prevent this traffic were added?
Anyway, I hope this gives you something to work with.