DNS error

I was updating a Wordpress site yesterday and got a message I was no longer connected to the internet (this happens a lot); when I reconnected, I could no longer access the website due to a DNS error. I can access the site using cellular data, but not on any WiFi-connected device. I have no issue connecting to other sites.

i spent nearly two hours on chat yesterday with three different agents and the issue is still not resolved. Other than changing providers, which I’m seriously considering, how can I get this fixed?