GoKawiiltrueCABLE testing shows Ethernet couplers degrade signal after three joins
An Ethernet coupler simply links two RJ45 sockets without boosting signal, and a single coupler usually works fine if connectors are solid. trueCABLE ran cable-tester trials using a Fluke DSX-8000 on various Cat6 and Cat6A cable-and-coupler combinations, finding that setups with three couplers generally passed (one barely), while four-coupler chains failed outright. The report also notes the standard 328-foot copper Ethernet limit still applies regardless of how many couplers are used.