openVPN peer to peer download limited by upload speed

[killertomate]

Hey,

i have two sites connected via OpenVPN peer to peer with a preshared key. Site A has a 400/20(server) and Site B 1000/1000(client)

Site B connects to Site A, when i know send traffic from B to A via the tunnel i get a limit of 20Mbit in download because for some reason it sends the same amount out. Is there a traffic verification happening or are there any other reasons for that? I also tested it without any encryption, same result. Im also not limited by the cpu and regular downloads get the full 400mbit

maybe you guys can help me