Cox → 50 Mbps Preferred Package on XP machines?

I got a new modem today from COX (cisco DPC3010) and hooked it up to my Netgear R6300 so I could take advantage of the new Preferred Package speeds. On my two XP machines I am still at 20 Mbps, but on my two Win 7 machines, my phone and my daughter's tablets I am getting 45-50 Mbps. Is this a known issue with XP? What am I missing? Thanks in advance for suggestions.

How are XP machines connected? Wired or wireless?

If wireless, how is the signal strength to those devices? How is the router configured for wireless settings?

If wired, it could be a limitation in your registry. I would bypass the router just in case, and go wired from modem to XP machine and see if still 20Mbps. If so, then try TCP Optimizer via link below. Make sure to back up your registry before making any changes though.

»www.speedguide.net/downloads.php

Figured it out, it's the wireless adapter on my laptop. It will not handle the higher speeds. All other devices are at or above 50Mbps.

This is a common problem with wireless. You get the latest and greatest 802.11 AC router only to find out that your wireless adapters are only good up to 802.11 B or 802.11 G speeds.

If you can't run wired and want or need the faster speeds you may be stuck getting a bridge that will go from wireless to wired or a USB adapter as it is unlikely you will find an expansion card that will have current speeds and work with older hardware.