Conflict between AWS site-to-site VPN (to a VPC) and non-AWS client VPN

Question

The AWS site-to-site VPN works, connecting our on-premise network to a VPC, but causes our client VPN (configured on our router) to stop working, i.e. remote users become unable to log into our company VPN. Before posting more details, can anyone say off the top-of-their-heads why this might be happening?

Answer

In the router's admin GUI, by deleting the userids of the users allowed to use the local VPN and then re-inputting the same userids and passwords, the client VPN was made to work. Comparison of the before-and-after ascii config files showed that some behind-the-scenes reconfiguration of tunnels was done by the GUI. Now, both the AWS site-to-site VPN to a VPC, and the client VPN that allows remote users to access our on-premise network are working.

Conflict between AWS site-to-site VPN (to a VPC) and non-AWS client VPN

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