I've always done this from my computer browser.
Login to your router at 192.168.1.254.
Select the Connected devices Tab.
Find a line Boost2-0-a640 (this is the Wi-Fi 6 device) or similar and record the IP address.
Enter this IP address into your browser and use the credentials on the Boost device to login to the web admin page. From there you should be able to find the IP addresses of any further devices, and access their individual web min pages.
It has been a long time since I did this, and am uncertain if it will work with more recent units.