I had this router Archer C2600 and i followed this tutorial, all it worked!
Try to stop the antivirus, firewall and all software that would prevent packet transfer.
If you are experimenting with C2600 and you flash the wrong firmware and the device doesn't boot, you can restore the factory firmware:
Set PC to fixed ip address 192.168.0.66
Download factory firmware from TP-Link and rename it to ArcherC2600_1.0_tp_recovery.bin
Start a tftp server with the file ArcherC2600_1.0_tp_recovery.bin in its root directory
Turn off the router
Press and hold Reset button
Turn on router with the reset button pressed and wait ~15 seconds
Release the reset button and after a short time the firmware should be transferred from the tftp server
Wait ~5 minute to complete recovery.
Good luck
https://wiki.openwrt.org/toh/tp-link/tp-link_archer_c2600_v1
https://forum.openwrt.org/viewtopic.php?pid=236428#p236428
