I checked the DSM auto-block list (empty), confirmed SSH was enabled in Terminal & SNMP settings, verified the iptables startup task was running, and ran a TCP port test — ports 22, 445, and 5000 all appeared blocked.
After all of that, I ran ipconfig. The PC was connected to the wrong Wi-Fi network.
What Was Actually Happening
I have two Wi-Fi networks at home. My NAS sits on one of them. My coding PC is supposed to be on that same network — but Windows had quietly switched it to the other one automatically.
The NAS was fine. The SSH service was running. The problem was that my PC and the NAS were on different networks and couldn’t see each other.
Most homes have one Wi-Fi, so this doesn’t come up often. An AI assistant won’t think to suggest it. I don’t think to check it either. That’s exactly why it eats up an hour every time it happens.
Check the Wi-Fi Name Before Anything Else
netsh wlan show interfaces | findstr SSID
If the result isn’t the network your NAS is on, that’s the whole problem. No port or firewall setting will help.
Secondary check — confirm you’re in the right IP range:
ipconfig | findstr "IPv4"
If the IP doesn’t start with 192.168.0., you’re on the wrong network.
🗂 Claude.md Rule SSH/SMB to NAS fails → check Wi-Fi name first (before ports, firewall, or DSM settings). Cause: two home networks; PC auto-switched to the wrong one.
netsh wlan show interfaces | findstr SSID→ must match the NAS network.
Time I wasted: about an hour. The actual check takes five seconds.