The slow download time for DSL compared to FIOS is expected. The DSL line that WPT is using is only about 1.5Mbps download speed, but FIOS is 20Mbps download speed. So FIOS is about 13 times faster than the DSL.
If you want the site to be faster on DSL, you have to do a number of things - two of the biggest are # of Requests and Bytes In. These should be reduced.
You are not going to get DSL to be anywhere near what you can get with FIOS, given those speeds, but you can get the site faster on DSL by making some changes.
For example, the site gets a “C” for compressed images. You should ensure that as many of your images are being compressed by the server, so that you can reduce the byte size of the data going over the slower DSL connections. This will use up less bandwidth.
If you look at the DSL bandwidth graph, you’re getting very close to using up the whole 1.5Mbps with many of the requests. If you compare that to the FIOS bandwidth graph, you barely get halfway to 20Mbps on the graph. So compressing your images, or better yet, making your images smaller without losing your desired quality should be considered.
The site gets an “F” for caching static content. You need to ensure that the client can cache as much content as possible to reduce the number of connections that are being requested for returning users.
I also see numerous 302 redirects. You need to reduce these as well, to minimize those requests.
In addition, another difference between the DSL and FIOS connections is the latency. DSL = 50ms and FIOS = 4ms. This difference is even worst than the speed difference.This means that with each request, you are adding a minimum of 50ms to your response time (without anything being processed yet) with DSL compared to FIOS, which only adds 4ms. So reducing the number of requests will help a lot by avoiding going across the network and incurring this 50ms penalty.
I can’t speak to any issues with the WPT machine and location itself. Maybe Patrick Meenan or someone like that may speak on that. However, your need to have the site be as fast or near as fast on DSL as it is on FIOS, if that is indeed the case, is not possible due to the bandwidth and latency differences that have little to do with WPT.