This is what I did and it worked: I bought a wireless router and hooked it up to the modem and connected my Chromecast through the new router I bought. Not ideal, and it shouldn't be necessary, but it works great. I tried nearly every other solution I could find. If nothing else works for you, try this.
I hooked up a wireless router to the device and connected the Chromecast to it.
Already have an account? Login
Enter your username or e-mail address. We'll send you an e-mail with instructions to reset your password.
Sorry, we're still checking this file's contents to make sure it's safe to download. Please try again in a few minutes.
Sorry, our virus scanner detected that this file isn't safe to download.
