@undefined Go through this solution and check if it helps in your case.

@splashscuba Replacing the cable between the ISP modem and AC1200 sometimes helps when it causes any issues. What else you could try is to connect a PC directly to the ISP modem and test the ISP...

@DougWeller Here's the tpPLC utility download page - I can see at least six Windows OS versions there. You should check what version you have installed and if there's a newer.

@splashscuba I would contact the ISP and ask them to check the connection from their side.

@LindaTee Nano stations receive their IP addresses according to the main router in your environment (old ISP modem or new Archer AX73). If they use different IP subnets or any router specific...

@DanielDT Set RE DHCP server to "Deshabilitar". Restart the main router, then restart the WA850RE. For improving your WA850RE performance you may read through this thread.