Honeywell T9 WiFi Thermostat Issue (w/ solution)

I'm not sure who else might run into this issue... So I thought I'd post here so perhaps someone having the same problem can use the same fix. I got a new T9 thermostat and got it all set up to the point of connecting to the home app. No matter what I did, it would time out trying to register (when connected to my home wifi). I used my phone as a hotspot as suggested by the support website. That worked, but when I switched the thermostat back to my home wifi it would show "Not connected to the Internet." I then tried a ton of different solutions trying to fix it to no avail. I was about ready to throw it back in the box and send it back. Instead I did some digging and eventually ended up pinging (or trying to) the IP address the thermostat was trying to reach. This lead me to discover that my ISP wants a smaller "TCP MSS" than the default in my router. So after several more web searches I was able to lower the MSS on my router and after applying the new router configuration my T9 showed "Connected to Internet" on the WiFi screen. So if you've exhausted every other option and it's still not registering give that a try.