Default password: TP-Link Archer C5 HW ver. 4.0

I trying to login on subject device with original TP-Link firmware through UART console. For gathering additional info about device.

I have prompt in console: Archer C5 login:
How do you think, what default credentials?

P.S. On TP-Link WR-1043N HW ver 5.0 throught UART connection just enough press ENTER and you are in root console.