Only one I ever tried is whatbox.ca . Been using them for 7+ years. They are great.

Haven't heard of private, but I would highly recommend airvpn. You could do qbittorrent nox on an old computer for good seeding. If you want I could elaborate on how, but I can't right now.

I wrote what's before this before looking at private. It looks okay but they definitely make some false claims in their marketing that make me skeptical. They say their VPN can make connection faster than non-VPN, that is only true if being throttled or smthn weird. They say it hides your IP from your ISP, which is impossible. Your ISP loans you an IP, of course they know it. I know they mean it allows you to use an IP that your ISP doesn't know, but they still said it wrong so.. idk im rambling and tired but... yeah. Response.

I have been using ultra for over a year now and dont have the issue you are talking about. How many seeds/peers do the torrents have? Might just be that there arent a lot of people dling what you are seeding

I am using Ultra.cc, and do not have issues with seeding

Ive used Ultra cc for maybe 7-8 months straight now and have a ratio of 40on my private tracker. 7+tb upload with the ultra service alone. Got a little over 100 seeding 24/7I was strategic in the beginning, only going for popular freeleech stuff. Packs are very popular. Ive seeded a ton of a cartoon pack I got for nostalgia, and it wasnt even a fresh upload when i grabbed it.

Edit, also im not using a vpn, for anything. Ultra cc's service can be used as a vpn tunnel. But since my host is in the Netherlands racks it doesn't need a vpn for public trackers, and i dont need a vpn to stream from the seedbox.

If you are testing upload speed better try with public torrent since it is much harder to seed on private trackers.

I dont use seedbox, but kinda happy with airvpn