Very slow transfer speeds over remote VPN connection (but fast speed over QuickConnect)

VPN
1

I have a strange problem with my DS218play at my home. The speed over the remote VPN connection from my office to my home is so slow that it’s unusable, I’m getting only speeds in the 2MBit range. Every other connection to other devices over the same VPN are working fine.

To make this post quick:

- the VPN connection is etablished from my office router to the home router

- from my office, I connect to the internal IP adress of the NAS

- everything regarding access over VPN to my DS218play is slow: SMB, AFP, FTP, DSM. DSM takes like 30 seconds to just load the login page.

- in the internal home LAN everything’s working fine

- if I remote connect to a PC at home and accessing the NAS over it, everything’s working fine. I can then transfer files from the home PC to my office PC just fine, but I don’t want to leave my home PC on the whole time.

- funny thing is, when accessing the NAS via QuickConnect, e.g. from my mobile phone, everything is working fine. The NAS maxes out my internet upload speed. So I’m not suspecting any firewall issue.

- all relevant service ports are enabled in my home router setup

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So with these points I don’t know where to look for a solution. Google doesn’t turn up anything useful.

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Edit (Solution):

It was the routers’ fault, which is bottlenecking the connection.

I installed a VPN server directly on the DS218play and setup an OpenVPN connection – the transfer speed is now maxing out my internet connection. Thank you all!

2
  • the VPN connection is etablished from my office router to the home router

Either your home router or your work router are bottlenecking due to being severely CPU constrained.

SSH to your router and check CPU utilization, if your router supports that.

To give you specific recommendations: What are those two routers and what VPN are you using? OpenVPN for example is not hardware accelerated and is done purely in software.

3

Is there an MTU issue? I’d take a look at what’s happening at the network level with Wireshark.

4

It’s established over OpenVPN and the routers both show no significant CPU spike when connecting to the NAS (20-30%). File transfer speeds from other devices, e.g. from my home PC to my office PC and vice versa via SMB are working flawlessly.

5

Most likely your routers cpu isn’t able to encrypt/decrypt your data fast enough.

6

Thank you for pointing me to the right direction, it is indeed the routers’ fault, which is bottlenecking the connection.

I installed a VPN server directly on the DS218play and setup an OpenVPN connection – the transfer speed is now maxing out my internet connection. Thank you all!