We have external services that are behind an Amazon EC2 security group, users connect to a VPN (this is supplied and maintained by a third party) so that they are given an IP that is consistent over time and accepted by the security group rules.

Multiple users can connect on their own networks and use the vpn/websites at the same time with no issue (most of our colleagues are work from home at the moment).

However we have just setup a new office network and are observing that multiple users cannot access sites behind the EC2 rules at the same time, what we actually observe is a flip/flop of access where one user will temporarily have access while the page will stop loading for the secondary user, and then the control will flip when the secondary user beings interacting with the site again. We would like to be able to access websites in parallel.

  1. Accessing websites not behind EC2 rule doesn't seem to be an issue while on VPN.
  2. We have tried different network providers (hot spotting off the same phone seems to result in the same issue, but the phone is a different network to what is being supplied to the office).
  3. Static IP is not an option we have available in this office (our network provider doesn't support static IP (https://ee.co.uk/)).
  4. Our IP address is IPv6.

Pretty lost with this one, any advice for how to investigate further to diagnose would be much appreciated.

1 Answer 1


Issue here was the VPN provided.

VPN installed was L2tp/IPsec VPN, the limitation of this is that it allows only one user from a particular public IP address to connect at one time.

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