mitmproxy issues

[GamingFourStars]

I followed the guide, but I'm having issues with step 6.

Once I set up the proxy, my phone (android) displays the wi-fi as "no connection" and in the app, it says the connection is unstable.

On the mitmproxy ui (windows 7, installed using exe), it keeps saying "clientconnect" and "clientdisconnect" every once in a while, which I assume isn't normal.

Back on my phone, when I get rid of the manual proxy, the connection returns to normal. But that won't work.

In this case, I can't get to the Splatoon 2 page while online and so I don't have the session cookie. Is there something I can do about it?