Ask them about their set up & try to emulate it. See what's different about theirs compared to yours.

But I have a suspicion this is more-so to do with those users who downld & upload great bandwidth & quantities which the isp is simply unable to maintain due to running out of bandwidth to share around. This is becoming a common issue amongst USA (& a no. of European countries) with reaching their full capacity & then having to secretly cut back upon those that use high bandwidth programs such as peer to peer, games, video-conferencing.

Thus the isp most likely picks on those that are in the higher bandwidth usage area, perhaps the top 5-10%. Of course they know which users are within the top %'s. They measure every individual's bandwidth usage up & down. This is similar to those ISP's in some places in the world that still apply bandwidth usage limits. And for those usa co's that use so-called unlimited service... By unlimited service .... it's not exactly that because the isp has a limitation of their ability. Once they reach near their total ability, then they must sacrifice certain users. So they base it around a certain calculated max per user they can sustain. If a user nears or reaches those bounds or beyond, then that is most likely the reason they will take steps to thwart that person's use. How catch 22 that is ... a business must expand to survive ... yet they are stuck with a limitation of overall bandwidth & traffic they can handle. So who suffers in the end with any expansion of userbase ...

BTW they save their bandwidth for their most profitable customers: Business.
Outside of business hours you "might" find better chances of alternate uses of their service such as p2p. Whilst all these things have proven to be true with other ISP's, there's so guarantee this is what is based behind OOL's total approach or whether there's alternative approaches that will work. But theys almost always have some opposition group in the market. Hopefully you have an attractive alternative in your area.