@neo4070 said in Why not same speed on LAN vs OPT (SG-1100)?:
How can pfsense so quickly "detect"/negotiate it to being 100 instead of 1000? I've tested it with my network cable tester and all wires in correct place. Something is wrong with this cable. And even if I get approx 100 MBits/s now - I still want to be able to understand what is wrong with it and if I can "trust" it...
Pfsense doesn't do that, the NIC does. If that's a simple continuity tester, it may show it's correctly wired, but not other issues, such as crosstalk. Anyway, it's easy enough to try another cable.