One Ethernet jack in my house is slower than the others. Iperf measures 1 Gbit/s between PCs on all other jacks, but only 95 Mbit/s to the slow jack. A network cable tester finds no issues with the cable going to the slow jack. However, all cables in the wall are Cat 5 (not 5e). Am I just getting lucky with all the other Ethernet jacks? Or is there possibly some other issue affecting this jack's speed?