Synology has awful speeds - trying Wireguard on openwrt router - Help with routing

[Bestaflex 0]

Hi all,

I have an older synology 1511+ under DSM 6.2 and use the synocommunity version of deluge (docker is beyond my tech skills, tried and failed a few times).

When no vpn is connected in the network tab of the control panel i get my usual speeds around 30Mo/s (240mbps) but then when vpn is connected i can't for my life get over 6Mo/sec (48mbps).

Could someone please review what i did and hit me on the head with some advice ?

Setup :

I set up the openvpn through that guidemaking sure i use a low charge server (tried 1 server, country and region without noticeable change)

I opened a port on the air vpn website and reported it in deluge as describded in multiple forum threads unchecking lots of previously checked boxes


 

Edited ... by Bestaflex

[reversevpn 9]

OpenVPN might just be too heavy for your synology NAS to do without sacrificing significant performance. Try wireguard instead.

[Bestaflex 0]

On 4/9/2026 at 10:07 PM, reversevpn said:

OpenVPN might just be too heavy for your synology NAS to do without sacrificing significant performance. Try wireguard instead.

Any guide or how to because it feels like wireguard and Synology are not natively liking each other.

All the guides i've found are docker or spk repacker (does not exist for 1511+) and seems to be done for incoming and not outgoing Edited ... by Bestaflex

[reversevpn 9]

Is it possible for you to insert a middlebox between your synology and the upstream router? By middlebox, I mean any computer that can run Linux (i.e. Debian) and that you can give at least two ethernet interfaces (oen or both can be USB ethernet if you don't have enough built-in Ethernet ports). If it is possible, you can have the middlebox do wireguard, then just set the mtu between the synology and the middlebox to be 1420 (or 1320, if you leave the AirVPN config file as-is), and then just have the middlebox NAT all the synology's traffic into the Wireguard tunnel.

[reversevpn 9]

If you can't dedicate a middlebox to just your NAS, you can use your main machine as the middlebox, if it runs Linux with systemd. If you do have that, then you can use iproute2 and systemd-nspawn to just send the NAS's trafic over the VPN without sending your main computer's traffic over the VPN, unless you also want to send your main computer's traffic over the VPN.

[Bestaflex 0]

On 4/13/2026 at 9:30 AM, reversevpn said:

If you can't dedicate a middlebox to just your NAS, you can use your main machine as the middlebox, if it runs Linux with systemd. If you do have that, then you can use iproute2 and systemd-nspawn to just send the NAS's trafic over the VPN without sending your main computer's traffic over the VPN, unless you also want to send your main computer's traffic over the VPN.

On 4/13/2026 at 9:25 AM, reversevpn said:

Is it possible for you to insert a middlebox between your synology and the upstream router? By middlebox, I mean any computer that can run Linux (i.e. Debian) and that you can give at least two ethernet interfaces (oen or both can be USB ethernet if you don't have enough built-in Ethernet ports). If it is possible, you can have the middlebox do wireguard, then just set the mtu between the synology and the middlebox to be 1420 (or 1320, if you leave the AirVPN config file as-is), and then just have the middlebox NAT all the synology's traffic into the Wireguard tunnel.

I dropped the Wiregard approach as while i found and spk, after that it's mostly SSh as there is no native UI and that's somehow above my paygrade (and as said all the guide i find for syno/wireguard are taylored for the server side or access point, no as an exit strategy).

I saw some post about raspberry middle box and i'll look into it thanks.

[Bestaflex 0]

Little update.

After i was advised to use Wireguard and that the NAS did not provide any native support i remembered i had an old tplink archer C7 lying around and wondered if i could do a middle box of it.

Long story short : I flashed it for openwrt, made it a dumb ethernet access point (no WAN, no DHCP, no wifi), installed wireguard and managed to setup airvpn.

I then connected the nas to it but now i have a bit of an issue : dumb AP works as even with the openwrt router between may main gateway (isp box) and the NAS i can find it and access the DSM UI fine but then when i activate the wireguard interface i loose connexion. 
The connexion from my PC is wifi to ISP box then ethernet to openwrt then nas. My take is that the wireguard interface tunnels all to the airvpn exit node and there is no way for me to reach the nas from the LAN with it's local IP)

Is there a way to dissociate so that the WG connexion is only for outside of the actual LAN (the DSM VPN system did that perfectly) ? May be some port routing black magic (because honestly i only need the torrent to go trhough the vpn, rest not so much)

BTW also noticed that with the WG interface activated, the tailscale network i use to reach the nas from outside loose trace of it when it never did it with the openvpn on DSM.

EDIT : after tweaking for hours i now have access to the devices after the router but the traffic doesn't go to the router and ip leak test show my torrents on my own. I found places where they seem to think that dumb AP and vpn client just don't work as the principle of dumb AP is to be transparent.