Can split tunnel be configured without impacting connected VPN clients

Can the split tunnel be configured on the fly or do the connected clients need to disconnect and reconnect to get the policy change if it is applied globally?

Routes are pushed at connect time. To add or remove routes, having the client reconnect is the simplest way. With Access Server if you make this change and press the Update Running Servers button, your clients affected get kicked/reconnected.

This has the same behavior with OpenVPN Cloud. If you make the change on the portal, all affected clients will be automatically disconnected/reconnected if needed.

In most cases, the disconnect/reconnect happens without user intervention needed. With this, most users do not notice it (it reconnects in the background and usually remembers authentication credentials).

Resolution: For more details on Split Tunneling, you may refer to the links below:

Split Tunneling with Access Server

Split Tunnel on Cloud

Access Server Resources:
OpenVPN Access Server Documentation
OpenVPN Access Server Resource Center
OpenVPN Access Server Admin Manual