@ksaro1 Sorry, I was delayed by personal stuff last week. As far as I know, Deco is the default LAN DNS server for the devices connected to the Mesh. But it did not support mDNS or local DNS...

@bolsoncerrado It seemed like when there is no internet, the ISP modem did not assign an IP address for Deco anymore-WAN/LAN auto-sensing. You could try to move the LAN devices behind a nearby...

@Skolgatan16 AC1200 is not the model. It should be something like RExxx. You could refer to the troubleshooting guide here: Unable to Connect to WiFi Extender or Saying Incorrect Password

@Chanda_321 What is the model number of your range extender? If you can't log into the web UI, maybe you could try the Tether APP. The configuration via Tether APP is quite easy.

@ksaro1 Did you try to change the DNS under the DHCP server to 8.8.8.8/8.8.4.4?

@fischema You should still set 400m/s or the internet speed from the first PX50. If you put 100m/s, then the whole PX50 mesh will be limited to 100m/s.