@Clive_A I understand the question, but I don't understand why this is unexpected or confusing. Router A has LAN subnet 172.18.0.0/16 and Router B has LAN subnet 172.19.0.0/16. So of course the...

@Clive_A I'm not sure what you mean by "Why is your IP address displayed as 127.?". I'm testing the speed between two servers on private 127.* subnets, connected by L2TP encrypted VPN. iperf3 speed...

@Clive_A iperf3 results: VPN client side initiating upload (client -> server): ``` $ iperf3 -c 172.18.2.1 Connecting to host 172.18.2.1, port 5201 [ 5] local 172.19.2.1 port 43756 connected to...

No, this is tested using the openspeedtest Docker image (https://hub.docker.com/r/openspeedtest/latest). It first tests the download, then tests the upload. They are not being tested at the same time.

@Clive_A Router A and B are installed in two different physical locations, so I don't really have any way to bridge them directly together. Here's the diagram:

@Clive_A It's not a ping/firewall issue, it's a DNS issue. I have a Windows machine with hostname "SERVER1" on the network, where the router (ER8411) has IP 172.18.0.1. Running `nslookup SERVER1...