Thanks for taking the time to reply, but it turns out it was a problem with my wifi - the physical link to my access point is connected at 100Mbps, not 1Gbps.
I ran some speedtests from a wired server last night, and they reached up to about 350Mbps (with around 60-70 upload). The download is still a little slower than my phone (which can reach up to about 450Mbps), but a lot more respectable, and the upload seems faster than my phone.