RDP Sessios slow over VPN

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skl
Posts: 4
Joined: Sun Mar 11, 2018 2:15 am

RDP Sessios slow over VPN

Post by skl » Mon Mar 12, 2018 1:12 pm

Hello guys,

I'm testing VPN Server as Remote Connection.
Routing, ping and throughput is ok.
However RDP sessions is very slow. Did packet pacture and saw a lot of TCP retransmissions (attached).
I saw this before in other tunneling situation because RDP is sensitive to fragmentation, where adjusting MTU resolved issue.
Could someone help me troubleshoot this case?

Environment:
Tested VPN Server in Ubuntu 14 and Centos 6.5.
Client connecting to VPN Server through HTTPS/443.
Firewall doing Full DNAT to Internal VPN Server.
Bridged to local LAN and getting IP from local DHCP Server.
RDP Server (2008 R2) is on the same network segment.
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thisjun
Posts: 2458
Joined: Mon Feb 24, 2014 11:03 am

Re: RDP Sessios slow over VPN

Post by thisjun » Thu Mar 22, 2018 7:07 am

I think TCP retransmissions doesn't happen.
Each packet is sent just once.

Could you try to disable the NAT-T?
Because packet loss of UDP may cause this problem.

skl
Posts: 4
Joined: Sun Mar 11, 2018 2:15 am

Re: RDP Sessios slow over VPN

Post by skl » Thu Mar 29, 2018 5:04 pm

Hello,

I'm using vpn over HTTPS, tried with 5555, too.
Also, VPNServer is inside the branch network published with DNAT. And on client side there's a NAT but allowing all traffic to outgoing.

thisjun
Posts: 2458
Joined: Mon Feb 24, 2014 11:03 am

Re: RDP Sessios slow over VPN

Post by thisjun » Wed Apr 18, 2018 7:04 am

Does SoftEther VPN client connect to the VPN server with TCP?
Could you confirm method of connection by log of VPN sever?

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