windows vm smb speed very slow after vpn certificate renewal

Question

I am using the Network Drive connected to the local Windows virtual machine via OpenVPN and SMB.
Recently, the VPN certificate expired, so after renewing the certificate, the Network Drive was connected.

Previously, the read and write speed of Network Drive was over 50 MB,
Since the renewal of the certificate, the maximum size cannot exceed 2mb.

It was strange, so I connected the Network Drive in the same way to a Window PC on another network.
The read/write speed is well above 50 MB.

I checked all the options, but I can't see anything different in the two VMs and PC.
If you connect another PC to the Internet modem and router that the VM is using and connect the Network Drive, the speed still comes out slowly. (~5mb)

When I measure the network speed in my Local Window VM, it comes out more than 500MB.
Oddly enough, very slow speeds come out only on NetworkDrive.

I do not know what is the problem.

I would appreciate it if you could tell me the answer.

Answer 1

Hi,

Can you check iperf and verify the connection + transfer speed using the iperf, this should provide some details around the speed and latency. Also configure the diagnostics on the VPN GW for investigating the root cause might throw up some pointers troubleshoot-vpn-with-azure-diagnostics

Iperf - vpn-gateway-validate-throughput-to-vnet

Upload the logs here and also raise a support case with Microsoft to investigate the backend routing.

Hope this helps.
JS

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