Xbox says I have 27% packet loss and MTU issues, which won't allow me to play multiplayer

MTU can be reconfigured on the router by yourself or by ISP. Kindly provide additional details:

• Wired or Wireless connection
• Speed tests results via Xbox
• Speed Tests done via any other device on the same network

You may have already tried this but if not try turning your modem/router off wait 10 seconds and then turn it back on.

The maximum bandwidth does not matter much in internet gaming. What matters is the latency and quality of the connection. If you have 27% packet loss it is amazing you get any game experience that's worthwhile.

Satellite and Cellular based internet service are not recommended for gaming.

What type of connection do you have?

Is your connection shared with any neighbors; IE cable internet tends to be a shared connection not dedicated. One of your neighbors could be the issue or the line overloaded.

We need.more.info

Isp

Type of connection

If you are using 3g or lte or satilite any non broadband connection

Then the massive packet loss is expected

You need a persistent broad band connection cable fibre or dsl

If ita a shared school or hotel hotspot connection then no there is nothing you can do

You are sharing a connection with multiple high speed devices

I'm having the same issue on 1Gig wired connection in Central Washington, USA. 961.06 download speed, 311.67 upload speed, 27 ms latency, 100% packet loss, 1480 MTU.