When using Umbrella Roaming Client, 127.0.0.1 is registered as the Windows DNS setting.
This specification may cause conflicts if DNS settings are changed by the VPN Client during the VPN connection.
It is recommended that you check to see whether your environment corresponds to the restrictions.
Umbrella Roaming Client (standalone): Compatibility Guide for Software and VPNs – Cisco Umbrella
https://support.umbrella.com/hc/en-us/articles/230561147-Umbrella-Roaming-Client-VPNs-and-VPN-Compat...
> The Umbrella roaming client binds to all network adapters and changes DNS settings on the computer to 127.0.0.1 (localhost). This allows the Umbrella roaming client to forward all DNS queries directly to Umbrella while allowing resolution of local domains through the Internal Domains feature.
> *The Umbrella roaming client is partially incompatible with VPN clients which monitor and force local DNS settings to remain the VPN-set values;