Network Troubleshooting#

The Network Troubleshooting page runs standard Linux network tools on the Octave device itself, so you see the network exactly as the device sees it. It never changes the configuration — use it freely, before and after every change.

Each card has its own Run button and keeps its last result. Long-running tools run in the background, so you can start several at once.

Button	Does
Run all	Runs every card with the values currently filled in
Export results	Downloads a plain-text log of all results — attach it to the support ticket
Expand all / Collapse all	Opens or closes every card
Clear results	Empties every card, for a fresh start

Every card also has Show commands & raw output, which shows the exact command and its output for the support team.

The troubleshooting ladder#

Network problems stack up: a missing route looks like a dead device, and a bad cable looks like a missing route. Test from the bottom up and fix the lowest step that fails.

Step	Question	Card	Good result
1 Link	Cable plugged in, port up?	Ethernet Link	Link detected, sensible speed (100/1000 Mb/s), full duplex
2 Address	Right IP and prefix on the right port?	Network Overview → Interfaces	Expected addresses on `eth0` / `eth1`
3 Route	Which interface and gateway will be used?	Route Test	Interface and gateway match your site drawing
4 Neighbour	Does the next hop answer on the cable?	Network Overview → Neighbors · Connectivity with ARPing	A MAC address, state `REACHABLE` / `STALE`
5 Reachability	Do packets get there and back?	Connectivity · Traceroute	Ping replies
6 Service	Is the Modbus / web port open?	Port / Service Scan	Port `502` open

The cards#

Ethernet Link#

Link state, speed, duplex and autonegotiation per interface (ethtool). No link means a cable, switch port or power problem — no setting can fix it. 10 Mb/s or half duplex points to a bad cable or a misconfigured switch port.

Network Overview#

Interfaces, addresses, routes and the neighbour (ARP) table in one view (ip -j). Compare it with your site survey.

Neighbour state	Meaning
`REACHABLE`	Answered recently — it's on this cable
`STALE` / `DELAY`	Answered earlier; Linux will re-check when needed. Still a good sign.
`FAILED` / `INCOMPLETE`	Asked, but nobody answered for this IP on this cable

Route Test#

Answers the most useful question: "For this destination, which interface, source address and gateway will be used?" (ip route get). Hostnames are resolved first.

Connectivity#

Ping (Layer 3), plus optional ARPing (Layer 2) on the interface you choose. ARPing asks "who has this IP?" directly on the cable, so it still answers when the device ignores ping, and it doesn't depend on routes.

Ping	ARPing	Meaning
✅	✅	All good
❌	✅	The device exists on this cable but ignores ping. Go to the Port / Service Scan.
❌	❌	Nothing answers on this cable for this IP — wrong IP, wrong port, or powered off

Port / Service Scan#

Scans predefined ports (Nmap) on one IP or up to a /24. Presets: Modbus, Web UI, Modbus + Web.

Port state	Meaning
open	The service accepts connections — the network is fine
closed	The host answers, but nothing listens on that port
filtered	Something drops the traffic — a firewall on the device or in between

Device Discovery#

Ping-scans a subnet (Nmap -sn, max /24) to list which hosts are alive. A full /24 takes 30–60 seconds. Useful to find a device whose IP you don't know — on eth0 subnets. For eth1, see Scenario 3.

Avahi / mDNS Discovery#

Lists devices and services that announce themselves (mDNS/Avahi) — for example other Octave devices. Filter by interface and by category: Web, SSH, Octave, Other.

Traceroute#

Shows every router on the way. Use it for devices behind a router to see where the path stops.

DNS Lookup · HTTP / HTTPS Test · NTP Connectivity · Octave Connectivity#

Internet-side checks — see No cloud / internet connection.

Common problems#

Symptom	Go to
A device doesn't respond at all	Device unreachable — step by step
Route Test shows the wrong interface	Traffic leaves on the wrong interface
A device behind a router doesn't respond	Device behind a router
A device works on and off	IP address conflict
No link, a `169.254.x.x` address, or the wrong DHCP server	Link down or no DHCP address
Local devices work, cloud doesn't	No cloud / internet connection
Ping works, but no Modbus data	Ping works, Modbus doesn't