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In the best case scenario, and in most in cases, ZeroTier connects peer-to-peer and none of your network traffic travels through our servers. This means transfers go as fast as your CPU & network can compress, encrypt and send packets, and how fast the remote end can receive them.
Network Resources
There are some cases, such as hostile NATs & firewalls in which your encrypted packets do indeed get relayed through our root servers. Relaying through our root adds latency. The packets must travel farther physically than they would for a direct, peer to peer connection.
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See Router Configuration Tips for more information on how to resolve such issues.
See also How do I allow ZeroTier through my corporate firewall?
CPU Resources
ZeroTier uses modern cryptography and has similar performance to tunnels such as OpenVPN, IPSec, Wireguard.
ZeroTier on a low powered, embedded device may not reach your full line speed.
ZeroTier uses hardware AES acceleration when available.
Why is a ZeroTier interface reporting a 10 or 100Mbps link speed?
It’s a virtual interface. It’s not really limited to that number.