Problem with tplink harware settings

It feels like its a dumb problem but I can't find any solution...

I have a 4Gbox with internet access. But wifi is bad through the 2nd floor (where I have 4G...). I always reached the box at 192.168.1.1.

I got the archer C60, then sent the internet access into a RJ45 to first floor into the archer C60. Now I have nice wifi, I reach the archer at 192.168.0.1. But now I can't reach the original box anymore at 192.168.1.1.

Is there a way ???

Thanks in advance so much