For Archer C6(US)V2
2 Download the earliest firmware from https://www.tp-link.com/us/support/download/archer-c6/#Firmware
5 Unzip it and rename the bin file
ArcherA6v2_tp_recovery.bin
Other steps are the same.
Also If no switch is working I was able configure my laptop Ethernet speed to 100mbps under Configure->Advanced->Speed&Duplex.