2 options of my planned set up for my wi-fi extension are in the image below.

Our 2 story townhouse is fully linked through multiple ethernet ports with the 'Home Base' for modum connection to the NBN placed under the stair well. This renders the wi-fi signal to the upstairs space as relatively weak.

I bought an Deco AX3000 Whole Home Mesh Wi-Fi 6 System to extend the wi-fi capability of my Archer AX2300 Modum/Router. Using the Deco app, I get through almost all of the set up for the base Deco unit, only to have it go from blinking blue to solid red, which means there is a problem with the connection.I have tried a variety of approaches:

- looked for other options to PPPoE as the designated 'Internet Connection Type' when requested (eg: 'bridge' or 'AP') but there appears to be no other suitable option.

- I am assuming my PPPoE username and password are those I have from initially setting up tp-link as our internet provider and I have used the network username and password we already have in place for our home wi-fi when the app requests a network id

- I have been entering X50-5G when asked what Deco unit I am attempting to connect to

Please let me know if there are flaws in either of the options presented below and advise/feedback on anything I should be doing differently in my app set up.