Just wondering if anyone knows the answer to this riddle.

Parents have got VDSL - they used to be (as from a month ago) on what might as well be a Conklin, 150m (line distance) from the serving cabinet. Their house was built in around 1890 with 1940's phone cable. I have been going through today removing all the old phone cable (really old, and corroded too) and replacing it with Cat5e.

I have done a test run after their VDSL speeds were lacking and have got from:

Download Rate: 61.02Mbps
Upload Rate: 9.8Mbps

To:

Download Rate: 72.83Mbps
Upload Rate: 14.2Mbps

on their router (I would expect DLM to give a faster speed) however real world speeds seem to be artificially limited:

Now, this speed was done over Gigabit Ethernet, their router is the Audiocodecs MP264 (ISP is WXC) and I have confirmed there is no errors on the line.

I could not get a clear answer out of WXC however do they rate limit their connections artificially or is this something I've overlooked?

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Edit: Title updated as it is just provider specific.