Why is download speed capped by MAC Address ?

Hi - thanks for coming back to me.

Please do not suggest it is the ISP - I am a network professional and can assure you the layer 2 local MAC Address does not leave my local LAN. MAC (layer 2) is simply not routable on the internet - only IP after being NAT'd to a non RFC1918 address (layer 3) is. As a MS consultant - I am very surprised you are not aware of this basic Ethernet knowledge.

To add - An ISP 'may' throttle traffic based on an IP port or dns (or packet pattern analysis) - but it will not be doing it via the devices local MAC - as it has no (direct) knowledge of this. The MAC is used by the switch/router ARP table to direct the traffic on the local LAN only.

Thank you for contact us! I'm Anderson, an Independent Consultant and a Microsoft user like you.

good morning

It is likely that your internet service provider (ISP) is capping the speed based on your MAC address to enforce a bandwidth limit. This is a common practice for ISPs to ensure that a single user does not consume excessive bandwidth, which can impact the experience of other users. If changing the MAC address temporarily fixes the issue, it suggests that your ISP is using MAC addresses as a way to identify and limit specific devices. However, Microsoft may not be acknowledging this because it is a practice imposed by the ISP and not by Microsoft.

Hi - d/l speeds are from the xbox x itself.

The xbox speed test says 930mbps, but the actual game download is about 600-700mbps - which is of course perfectly fine. I fully understand and accept that I'm not going to get the full capacity all of the time - but restricting to under a 10th of what the line is capable of is not on - especially when game downloads are typically 100-130 Gbytes in size, meaning multi hour downloads are required. PS5, Steam etc doesn't have this restriction - so I'm not sure why MS does.

I'm going to try a few more things such as VPN and changing MAC again to see if this is 100% related to the local MAC or maybe other factors exist.

Download speeds are throttled on Microsoft's end as well based on server load and the size of the item being downloaded. I would also speculate that when you change your MAC you're clearing cache and other things that can help improve speeds temporarily

My first 14.4 modem had to reconnect every 15-20min because it wouldn't properly empty its buffer

I can tell you that game downloads are capped at 2-300mbps typically under optimal conditions

Are those numbers from Speedtest or from the dashboard test?.

I have an a Asus RT-AC68U with dd-wrt, so I know it's an option if the info was available regarding which ip addresses and other connection info were available to the public. And if I could connect the ethernet and WiFi at the same time it would help because
then I could assign ports to different Mac addresses and prioritize or cap speeds according to those macs.