Found a solution (that worked for me) for slow xbox one download speeds that I hope might help somebody with the same issue as me.
I have recently installed a 100/10 fiber line, and got full speed with everything - except my xbox one. I barely got over 500kb/s which frustrated the hell out of me.
After a couple of searches somebody proposed changing the DNS settings in the xbox one from 'automatic' to google's DNS (8.8.8.8 and 8.8.4.4), which I tried last night. Reset the Xbox one and instantly I got full download speed!!!
I am not a techie so don't know why or how this work, but for me it really worked.
Halo 5: Guardians is available for pre-load but the process is taking too long due to slow download speed. Thankfully, multiple fix is available for Halo 5: Guardians slow download speed. Jump to Fix slow download speeds over Xbox Live - Fix slow download speeds over Xbox Live. Open the Settings app on your Xbox One. Navigate to the Network tab. Open Network settings. Select Detailed network statistics on the right side of the screen. XBOX ONE downloads incredibly slow. The Xbone does installs/updates slow. I have 50 meg service and it takes forever to download on my Xbox one, yet I can download a game in about 20. Slow download speeds in Xbox One S fixed in latest preview builds Kit McDonald Email @ Sep 12th, 2016 in Latest news Xbox One S users have been suffering through some performance issues.
Xbox One Slow Download Fix Windows 7
Microsoft
How to Increase Xbox One Download Speed. Of connection you have, there are a few things you can do to troubleshoot and improve slow download speeds. So this works great for me. However, after ~20 minutes the download speeds would go down to ~250kB/s again. The temp fix I came up with was Just clearing the MAC address again and doing the restart again and it seems to work. You just need to monitor your bandwidth usage in the network settings of the Xbox and clear when you get slow speeds. XBOX ONE downloads incredibly slow. The Xbone does installs/updates slow. I have 50 meg service and it takes forever to download on my Xbox one, yet I can download a game in about 20.