Agree with Gray-Blue7 a TP-Link AC router with Gigabit ethernet ports is a good choice. Most AC routers will support IPv6 which you want. I have the Archer C8 connected to a Motorola MB8600 with...

If it was me, I would exchange it for a new one.

Do you mean you cannot log on to the router or to a specific site such as TPLINK.Com. If it is the router, I have had issues signing on time to time on my Archer C8. Sometimes http://tplinklogin.net/...

By not appear, do you not see it on your device? Be sure you have the "Enable SSID Broadcast" set on for the 5g. Also check your mode (11A/N/AC mixed).

I have had issues signing on time to time on my Archer C8. Sometimes http://tplinklogin.net/ will fail where http://192.168.0.1/ will work or the other way around. Connect with tplinkwifi.net via...

Do you lose both the WIFI and LAN on the C60? If only WIFI, try a different channel and try powering down all the WIFI devices then up one by one to see if one of them may be causing an issue.