Earlier today, I received a comment from @RyanMeray on twitter, and on my blog post PPTP VPN, dd-wrt and private DNS resolution. Ryan’s transfer bandwidth across the VPN is 150Kbps, despite having upstream bandwidth of 4Mbps – and he wondered what my experience was.
I’d not noticed things being slow, but I hadn’t ever checked. I don’t know what work’s upstream bandwidth is these days, but I’m on a contended 50Mbps cable service at home and I wondered whether I could max out the CPU on the router (which I’ve now upgraded to a Cisco Linksys E3000).
My domestic upstream and downstream bandwidth:
Try broadband speed test
I started a large file transfer from work to home, and then hopped to dd-wrt’s bandwidth monitoring page:
a fairly steady 2Mbps.
dd-wrt’s router status page showed CPU utilisation:
maxing out at 50%.
The CPU is a 480MHz Broadcom chip, which is reasonably fast – but is the same chip as Ryan’s ASUS RT-N16. So it seems unlikely that this is what’s causing his VPN bandwidth to be clipped to 150Kbps. I’d be interested in gathering more data – so if you’re using the dd-wrt pptp client, please comment with your maximum throughput, router model, CPU speed and CPU utilisation. Thanks!