Extremely slow PPTP download rate

[AsusMerlinNoob]

Heya, I've been banging my head against every wall to realize what is wrong but I couldn't solve it so I made an account here to see if I can get any expert help.

Here's my issue:
I have an ASUS RT-AC88U router running the latest merlin firmware and my own pptp vpn running on it off of a Centos 7 server.

My usual download speeds without the VPN are around 100-150 Mbps but when running the VPN, my download speeds barely break 1 Mbps...
Upload speeds don't change much, the drop is kind of expected.

I've also tried running the same PPTP server on a D-Link with dd wrt and it runs with speeds that you would expect.

I understand that PPTP is obsolete at this point but I need it for a specific use.

Any advice would be appreciated, thank you.

Edit: Happy new year!

 

[AsusMerlinNoob]

Bump. Anybody?

 

[ColinTaylor]

I can't really follow what you said. Where/what is the VPN client, and where/what is the VPN server. How does the Centos server fit into this, is it running a VPN client or server?

 

[AsusMerlinNoob]

I can't really follow what you said. Where/what is the VPN client, and where/what is the VPN server. How does the Centos server fit into this, is it running a VPN client or server?

Thanks for your reply.
The server is a Centos 7 machine running the pptpd service and the client is my RT-AC88U on the latest merlin.

 

[ColinTaylor]

So the RT-AC88U is at location A, and there is another router at location B that is forwarding the PPTP ports to the Centos server on its LAN. Correct?

 

[AsusMerlinNoob]

So the RT-AC88U is at location A, and there is another router at location B that is forwarding the PPTP ports to the Centos server on its LAN. Correct?

Technically yes, the RT-AC88U is sitting in my home and clients in my home are running off of it and the Centos 7 server is sitting on a cloud machine running the PPTP server.

 

[ColinTaylor]

Can you try a PPTP client simply running on a PC. If you experience the same issue it would indicate that it's a server-side problem.

 

[AsusMerlinNoob]

Can you try a PPTP client simply running on a PC. If you experience the same issue it would indicate that it's a server-side problem.

I have done that, on a windows PC and DD Wrt router and the speeds are fine. The issue only seems to be on the merlin router.

 

[ColinTaylor]

Sorry, no idea then. But I don't use PPTP myself.

BTW On the Asus there are two places to configure "PPTP", WAN > Internet Connection and VPN > VPN Client. I don't know what the differences are.

 

[RMerlin]

WAN is for ISPs that require PPTP to connect to the Internet (mostly a few Russian ISPs), while VPN page is for connecting to a server through your existing Internet connection.

 

[AsusMerlinNoob]

WAN is for ISPs that require PPTP to connect to the Internet (mostly a few Russian ISPs), while VPN page is for connecting to a server through your existing Internet connection.

Any idea on my problem?

 

[RMerlin]

Any idea on my problem?

Either MTU mismatch or incorrect QoS rules being applied. I don't know.