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

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.