Always leaf, relay and poor connection

Hi,
I have 2 pc’s with zerotier client, one pc is behind a phone’s hotspot, the other behind a 4g router. They both seem to be leaf and communicate by relay according to cli. The router and phone’s network are probably limited by Carrier-grade NAT but this i am not sure of. There is a connection between the pc’s but very little data is coming through.
I gave zerotier a go because i read that it would handle situations where you cannot port forward. Is there anything to do or is my case mission impossible with zerotier?

Hello,
sorry! there’s probably not much you can do. That’s a really hard combination of NATs. Maybe you can ask your ISPs for help?

For situations like this I think you need some 3rd machine with a public IP, that everything else can bounce through (a cloud virtual machine)

Talked to my ISP today. They dont sell public ip’s and they dont know what port forwarding is about… When thinking of torrents , the link here How to Download and Play Torrents (with Pictures) - wikiHow describes how the torrent technology utilize ‘UPnP and/or NAT-PMP’ to start transfers without changes to firewall or router settings. My pc behind the phone’s hotspot can do torrenting and clients can download at an ok speed from that pc on the hotspot. In speedtest, the pc on the hotspot can probably transfer at 10/10 Mbps, on good days a bit more. Why can the torrent technology work but not zerotier?

Good question. It’s the mostly combination of 2 the difficult NATs.

Hard NAT <–> Public IP: possible
Hard NAT <–> Easy NAT: if you’re lucky
Hard NAT <–> Hard NAT: not likely.