Some of these live in my go-bag. Some run on a laptop. All of them have saved time at some point.
A network cable tester takes five seconds and tells you whether a cable has a wiring fault, a broken pin or a crossed pair. Buy one. Stop guessing whether the cable is the problem.
If you run cable, you need a punch-down tool. The impact type is faster than manual. Keep a stock of Cat6 keystone jacks — you'll always need more than you think.
For Wi-Fi troubleshooting, start with a free app like WiFi Analyzer on Android. For serious RF work, a USB Wi-Fi adapter with monitor mode — the Alfa AWUS036ACH is the standard — opens up packet capture and channel analysis that a phone can't do.
Still the best network scanner after 25 years. Scan your subnet, enumerate open ports, detect OS versions:
nmap -sV -O 192.168.1.0/24Run it against your own network monthly. You'll find devices you forgot you added.
Packet capture and analysis. When something behaves wrong at layer 2 or 3, Wireshark shows you exactly what's on the wire. The display filter syntax takes an hour to learn and saves days of guessing.
If you run a homelab with more than ten devices, document it. NetBox tracks IP assignments, VLANs, rack layouts and cable paths. Run it as a Docker container and keep it updated — future you will be grateful.
Tests actual bandwidth between two points on your network. Paste this on two machines:
# Server:
iperf3 -s
# Client:
iperf3 -c 192.168.1.xIf your 2.5GbE switch says 2.5Gbps but iperf3 shows 800Mbps, you found a bottleneck.
Keep these in a small bag near your patch panel:
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