orbio and expressvpn

It depends on how you were using ExpressVPN.

Residential WiFi routers do not interfere with the use of VPN by devices connected to the system.  A customer might have

• A laptop using NordVPN
• A tablet using Express VPN
• A smartphone using some other VPN

This is "all good".

The issue is that vendors bundle different types of VPN software in the router itself.  There are two basic types of VPN

• VPN Host.  This feature allows devices that are on the internet to connect through the router to devices on the local network.  Netgear routers support OpenVPN in 'host mode' for this purpose.  Some other vendors support OpenVPN and also other types of VPN.
• VPN Client.  This feature allows devices on the local network to all share one VPN "tunnel" through the internet to a VPN Host, such as NordVPN, ExpressVPN, etc. etc.  Netgear does not include this feature in their routers.  It appears that Asus may be one of the vendors which bundle VPN Client as a feature.
  https://mashable.com/uk/roundup/best-vpn-routers-uk 

So, if ExpressVPN is running on specific devices, then the Orbi system supports that just fine.  If the Asus router includes a VPN Client feature, then you have some choices:

• Install ExpressVPN on individual devices, or
• Purchase a device which supports VPN Client mode.  For example, the Brume 2 supports VPN Client mode for a number of VPN services, including ExpressVPN:
  https://www.gl-inet.com/products/gl-mt2500/ 
  The Brume 2 is available on Amazon for $80 (US, plus tax and shipping)
• Keep the Asus router and use it as the internet gateway for specific devices. (This would be similar to installing a Brume 2.)  It would require configuring those devices to use the Asus as the internet gateway (static setup) rather than accepting the Orbi router as the gateway.