Slower speed over VPN in Merlin than AsusWRT

[Evian]

Hi,
today i installed the MerlinWRT on my ASUS RT-AC86u after reading a lot of good stuff about it. Installation was easy, settings mostly didn't changed.
Exceptionally a few has to be changed in OpenVPN client.

The only things i changed were:
Redirect Internet traffic: YES (for all)
Accept DNS configuration: Strict

KillSwitch: ON

After checking about DNS Leaks just above strictly it does work. The other thing is that it is not working flawless after changing the server, often the internet does not work.
But my biggest problem is that i lost at least 10-20Mbit/s DL-speed in difference to asusWRT.

How is this possible? It's not even reaching 40% of CPU-limit

 

[eibgrad]

To be honest, a difference of 10-20Mbps is NOT a significant amount, esp. given what that router is capable of. I would have liked to have known the absolute DL performance rather than merely the difference. It's certainly well within the normal and expected margin of variability due to the VPN provider, which server, time of day, etc.

 

[Evian]

My ISP delivers 200Mbit/s
VPN:
Client 1: 50Mbit/s
Client 2: 40Mbit/s
Client 3: 70Mbit/s
Client 4: 50Mbit/s
Client 5: 70Mbit/s

The first score were done with DNS config: strict.

The first improvement is after changing to DNS Config Exclusive
Client 1: 70-80Mbit/s
Client 2: 40Mbit/s
Client 3: 70Mbit/s
Client 4: 70Mbit/s
Client 5: 70Mbit/s ~70% CPU

 

[eibgrad]

IIRC, that router is capable of considerably better throughput, well over 100Mbps. It has a 1.8GHz processor! So it seems to me the limiting factor is your VPN provider.

As far as Strict vs. Exclusive, that only determines how DNS is handled. And for speed test purposes, DNS shouldn't be much of a factor. The only difference between the two is that Strict reconfigures the local DNS proxy (DNSMasq) to use the VPN provider's DNS server(s), while Exclusive configures the client itself (indirectly w/ a DNAT) w/ the VPN provider's DNS server. IOW, in the latter case, there is no intermediary/proxy. But again, in a speed test, DNS is NOT what's typically being tested.

Are all those OpenVPN clients using the same VPN provider but just different servers?

 

[L&LD]

When you flashed the RT-AC86U with (which?) RMerlin firmware, did you do a full reset on it afterward? Without using a saved backup file to configure it either.?

 

[Tech9]

This router can do >220Mbps on 384 firmware and >160Mbps on 386 firmware. I never tested OVPN on the new Asuswrt, but it's like 6 months newer base compared to last Asuswrt-Merlin and some differences are expected. 50-80Mbps is perhaps VPN server limitation.