You are barking up the wrong tree.
You are saying that your Steam Deck is not working with the wifi at your home but there is no issue with it working with airport, in-flight, and hotel wifi.
That immediately tells me that there is no issue with your Steam Deck but the POS router that your ISP has provided.
You need to:
A: call your ISP and get them to fix their broken POS router.
B: At a later time get your own wifi router then call your ISP to put their useless shit into bridge mode so you can use your own router.
That’s why I stopped buying from the big brand manufacturers.
So many “system updates” that come out just before the new version is announced & suddenly your device is glitchy, slow and having constant problems.
I have been buying Nokia phones ever since. They aren’t the fastest, have huge storage, nor all the flashy bling of the “flagship” products but over the years I have found that I don’t need them.
Hell I even have a digital audio player so I can get better quality audio in a device smaller than most phones (plus I am not paying to rent music using streaming services).