@Tony Hi there, thanks for the reply. I was actually able to sort this out over live chat with TP-Link support. Turns out it was a DNS issue. Thanks regardless.

@jomama341 Here is what my network settings look like in OS X: https://imgur.com/a/pYiSXqf I've also tried swapping ethernet cables and that didn't fix it.

I recently purchased a TP-Link Deco M5 mesh kit for my apartment. So far so good with the wi-fi. The problem I'm running into, however, is that I can't figure out how to get the second ethernet port...