Slow speeds (40–60 Mbps) when using ProtonVPN on ASUS ZenWiFi AX router (1 Gbps line) — what am I missing?

[Philip Rohrhuber]

Hi all

I’m hoping someone can help me troubleshoot slow VPN speeds on my router setup. I posted this also on Reddit, but this place might be a better place.

Setup:

• Router: ASUS ZenWiFi AX mesh v1.0, newest firmware
• VPN: ProtonVPN (paid – Unlimited plan)
• Protocol: OpenVPN (configured via router)
• Server: Local country server (~35% load)
• ISP: 1000 Mbps fiber connection
• DNS: Using Quad9 (9.9.9.9)
• No other heavy traffic during tests
• Testing via Speedtest.net

Issue:

• Without VPN: ~900–950 Mbps (as expected)
• With VPN enabled on router: only ~40–60 Mbps download
• Also I just tried with Wireguard. Gets me to around 230 Mbps up/down.

What I’ve done so far:

• Followed Proton’s official ASUS setup guide
• Chose a nearby server with low load
• Verified no QoS or bandwidth limiter is enabled on the router

1. How do I get maximum speeds??

Thanks!

 

[Tech9]

How do I get maximum speeds?

You are already there. This model router can do ~100Mbps max on OpenVPN and anything WireGuard will slow down the entire network behind it to about ~250Mbps due to NAT acceleration incompatibility and lack of flowcache bypass in firmware.