Can't get wifi to connect on phone with Arcadyan KVD21 gateway

I've had my gateway since first getting service like two years ago. For the first year and a half or so it worked perfectly. Now I can't connect to wifi through my phone with it. It'll show up, and it'll occasionally say it's connected, but says no internet is available. Since I can't get internet, I can't get to the app to check my settings. My TV, which is right next to my gateway, has occasional wifi issues, but usually connects just fine. I have nothing else connected wirelessly, only a PC and PS5 connected by Ethernet cable.