Hi all!

I have an Archer C60 configured as an Access Point in my house's network for almost 2 years. A few time ago, after a support from my ISP, it stoped working well.

I've been trying to reconfigure it but I've been having some problems. Sometimes I can't connect some devices through wi-fi (error: connected, without internet) and even when I can connect, it hand on strange IP's.

My ISP main router is configured on 192.168.1.XXX and I configured my Archer C60 with static LAN IP according to that, as instructed on https://www.tp-link.com/us/support/faq/417/. However, when I connect any device to it, it is handing out 176.78.117.XXX (LAN) or 85.241.112.XXX (Wi-Fi).

Moreover, after configuring it and connecting my ISP main router to any LAN port, I immediatily become unable to access the configuration page again. I try the default gateway I configured, I tried those showing up on my devices (laptop, smartphones, etc.), I try tplinkwifi.net but nothing works so, everytime I want to try any change, I need to do a factory reset.

All the firmware is up to date on both router and AP and everything seems to be working fine and well configured on main router.

Already lost a lot of hours looking up for a solution but can't find the problem. Any help would be much appreciated.
Thanks