Greetings, all!

I am at a loss and need any guidance.

I just upgraded my internet to 400M down and 20M up. I was getting a max 20 down and 1 up on all devices. I have confirmed with Spectrum that all is good on their end via a home visit today.

So I factory reset the Deco and voila, better speeds, kinda.

On mobile devices (iphone, ipad), I get really good speeds, anywhere from 400/20 in the same room as the Deco to 165/20 sitting in my back yard.

On my laptops or my kids' chromebooks, the speeds are horrible. I just ran a 9.74/15 in the same room as the Deco. So decent up speed, but lousy down speed.

My laptop has a 802.11ac, so it should be able to eek out a bit better than this. In fact, if I plug my old router back in, I can get 121 down on my laptop. That's nowhere near 400, but it's better than what I'm getting now.

So apparently Deco loves my mobile devices but hates my laptops and chromebooks. Why?

Any ideas or suggestions here? I'm not a super tech savvy person. I know enough to be dangerous. Or maybe a bit less.

thanks in advance!