On 2021-11-27 4:36 p.m., Carlos E. R. wrote:
A continuity tester is not enough.
I have a normal multimeter which can be used with some care to test an ethernet cable. But a continuity tester doesn't find out if the pairs are connected properly: you know that the two pin in the centre are a pair, surrounded by another pair, but pins 1&2 are a pair. It is not 1&2, 3&4, 5&6, 7&8 (which makes it a pain to connect the cable to the jack, it uses a weir sorting. AND if you don't follow the proper sorting (there were cables like that), a proper tester finds out. The cable works at 10 mbps, but not 100 mbps. But in both cases, good and bad, an continuity testers finds no problem (pin 4 is connected to pin 4 on the other end, etc).
First off, I have connected many Ethernet cables, mostly in office where I connect jacks to a patch panel. I keep a tester similar to this one in my computer bag. https://www.amazon.ca/Flexzion-Network-Ethernet-Indication-Countunuity/dp/B017SM0G1U/ref=sr_1_6?keywords=Network+Cable+Tester&qid=1638049041&sr=8-6 Wiring errors or failed connections will cause the connection to drop from Gb to 100Mb, but I've never heard of that dropping to 10Mb. Regardless, if you actually need a better tester, get one, but the continuity tester meets my needs, unless the customer wants certification. Also, the wire order is not weird if you know the history of how StarLAN, which became 10baseT was designed to work over existing telephone cables which were 3 pair CAT3. With that phone cable, the middle pair was the phone the next pair was on either side of it and again with the 3rd pair. After moving to 4 pair cable, there were individual pairs available on either side of the cable. https://en.wikipedia.org/wiki/StarLAN