Devices cannot find Wifi Mesh extender's IP address and will not connect

Hello I've recently purchased an AC1750 Dual Band wifi mesh extender and although I've been able to follow the steps to get it connected to main router, create the network extentions for both regular and 5G service that are being picked up by multiple devices, and access the mywifext.net site which shows all systems in good shape, I cannot get any device to connect to either of the aforementioned network extentions. I'm getting the message (on my phone as an example) that "Couldn't get IP address". Has anyone experienced this or does anyone have any idea why I'm running into this issue? I appreciate any help!