Internet Air slow when connected to VPN?

VPN
1

I have AT&T Internet Air for a year now. I really like it. However, when I connected to my work VPN, it’s very slow:

No vpn : 162 down / 6 up

with vpn: 8 down / 1.6 up

Of course I understand that VPN adds overhead, but I did not expect it to be at this scale (1/20).

This is on a Windows 10 host.

Are there anything I can do on my side? On the router?

Thank you!

2

Hi. ATT Internet Air’s routing is very different than your cellular provider’s hotspot routing. Even if it is an ATT hotspot. The routes and latency from my Internet Air versus my Cricket (ATT) data line are night and day different (same LTE/5G Bands and signal levels). Cricket has less latency and regionally proximate routing. The route ATT Air is taking to your corporate VPN endpoint could very well cause a noticeable throughput drop. I have zero proof that is the case here, but FWIW, I wanted to add my experience.

3

Some VPNs add padding to the payload and it exceeds the MTU and that’s make the performance bad.

4

VPNs are limited by the server your connecting to.

Call you IT dept

5

And in my experience VPNs and internet error don’t really play that great with each other sometimes.

6

Thank you so much for sharing your experience and I appreciate it.

I did suspect as such but I just don’t have enough knowledge to confirm or deny my own suspicion :slight_smile:

Do you know if there is a way to fix it on my end? It’s just so slow. It’s usable but barely.

Thanks again!

7

I did experiment with different MTU sizes, no difference. Default is 1500. Beside, when I use my phone as a hotspot to the same VPN server, it was fast. So that means it had nothing to do with MTU?

8

Thanks. But it didn’t look like it the VPN server.

- when I used my phone as wifi hotspot, with same computer, I got:

no_vpn = 281 down / 6.4 up, with vpn to the same work server = 160/5

and this is an expected and acceptable result. So my work VPN has nothing to do with the slowness, yes?

By the way, the phone is on its own AT&T 5G.

Also, I’m not sure if this matters: I and my work are in SoCal but my IP is in Arizona. Does it mean it’ll take more unecessary hops as cause of the slowness?

9

No problem at all. Run an ICMP traceroute to the hostname of the VPN server via your Air connection and via your Hotspot connection. You can compare, and can also see if there’s a hop(s) that has a latency spike. On my Air, I had two weeks where I was routing out of netblocks in Florida and I’m located in the Northeast. I reset my connection and reset my public IP in my Air gateway every day to no avail. Two weeks in, I finally got back on a netblock out of Connecticut. Latency was night and day better, and throughput via my VPN (which is regionally close to me) was significantly better. I have a post on Reddit outlining it.

10

You don’t always see the VPN padding. But it also could be a routing issue.

Unfortunately other than using a different VPN server, there’s nothing you really can do.

11

Acknowledging that both of your tests are 1st-party, ATT could very well be traffic shaping, just like how they do with MVNOs.

12

Thanks again! I’m in Los Angeles (and my company too) but my Internet Air IP is in Tucson, AZ. I think it changed once in a while so I have no control.

13

Thanks. I connected to a few different VPN servers from my company and they are all slow.