Best VPN for small business with multiple users and need for static IP address?

Title says it all. Basically, I am looking for a pretty simple but scalable VPN service. We are an ecommerce agency, but some of our clients want their website’s backend hidden behind whitelisted IP addresses, so figured a VPN would be best for this.

We don’t do anything illegal so I really don’t care about logs or anything. We just need to have a static fixed IP address for our employees to access these backends as long as they’re connected to the VPN.

Does anyone have any recommendations? We’ve been using Outline VPN on a DigitalOcean server, but I find the manager to be annoying.

Thanks!