There isn't a free version of that software at this time. Kind of sucks, but you'd have to spend $11 for a 1 month trial to see if it works for you.
It sounds like you already have, but I strongly suggest trying out other options first before you'd consider paying for something like this.
If you haven't tried configuring your ports or aren't sure exactly what to do, please try out the monk's guide. He wrote it some time ago for the DG community and it explains what you need to do really well:
I don't believe bananaman had issues connecting to other users. His issue is specifically related to ping spikes and apparently his ISP throttling the connection speed on those ports. If you can't connect to other users period, that generally means a port issue. For instance, if you ISP isn't allowing traffic on certain ports or if you have things configured incorrectly and are actually blocking the ports you need yourself.
Anyway, I'd start with the monk's guide if you haven't. While you are doing that, send off an email to email@example.com and explain the specifics of your connection problems. And as a last resort, I'd say give the software bananaman is using a shot. That software appears to allow you to bypass port limitations imposed by your ISP due to how their VPN works. Good luck!