Many paywall websites, particularly for refereed journals like IEEE have been enabling IPv6 access. This becomes a problem when your institution (or at least their VPN) is IPv4 only, and your laptop connection is IPv4 + IPv6. The IPv6 may leak around the VPN, causing authentication failure to the paywall website, despite using VPN.
Fix VPN IPv6 leakage
The workaround is to create a separate profile in NetworkManager. You can make this profile your main profile if you don’t ever want IPv6. Let’s call this new profile “LANv4”
- NetworkManager → General → UNCHECK “Automatically connect to this network when it is available”
- IPv6 Settings → Method: Ignore
Connect to VPN by:
- select LANv4
- In Ubuntu desktop toolbar, Disable networking, Enable Networking
- Connect to VPN
Verify no IPv6 on VPN
It is possible to disable IPv6 persistently by adding to
net.ipv6.conf.all.disable_ipv6 = 1
but I want to use IPv6 most of the time.