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vectro

Member

Registered: 2016-10-15

Posts: 14

Specific sites not loading through OpenVPN

I'm having issues with OpenVPN behind a double NAT, and wondering if anyone could point me in the right direction.

I'm currently traveling and behind a double NAT (over a 4G modem). My home internet isn't behind a double NAT and I'm able to connect to it through OpenVPN and use most web services. Same goes for privateinternetaccess OpenVPN. Websockets work, most websites work, and my public ip address moves to that of the VPN server.

My issue is that certain sites just refuse to load on my home OpenVPN, or even the privateinternetaccess OpenVPN. Namely: Netflix.com and my university outlook account.
I can ping them and get zero dropped packets, but no html...
The confusing part for me is that if I use PTPP or SOCKS, everything works.
My traceroutes show expected behavior for both OpenVPN and PTPP. Packets are traversing the VPN just fine.
Also it's worth noting that these sites also don't load through the double NAT (VPN off). Only through PTPP or SOCKS.
EDIT: I can access them with no VPN if I boot into windows... Completely baffled...

How should I begin diagnosing this problem?

Last edited by vectro (2017-08-26 18:16:15)

brebs

Member

Registered: 2007-04-03

Posts: 3,742

Re: Specific sites not loading through OpenVPN

Sounds like the usual "default MTU of 1500" vs "MTU needing to be less, and ICMP is blocked" problem.

Example test:

ping -M do -c 1 -s 1472 ms.com

Google can help.

vectro

Member

Registered: 2016-10-15

Posts: 14

Re: Specific sites not loading through OpenVPN

Yes! That was the problem. I lowered the ping MTU until I got a successful hit. Setting it though my network manger fixed it globally. Thanks brebs. I'll be doing more reading on this ASAP.