I believe that error is for on-premises detection. In your client configuration, is that the host you have defined to check for on-prem/off-prem? If so, is that viladochaves.local defined as a private app? What I suspect is happening is that your on prem detection host is in a private app definition so the client see itself as off prem to start when that isn't able to resolve, then NPA comes up and it is resolvable so the client sees itself as on prem which is causing the client to flap. If that is the case, please ensure your on premises detection host is set to somthing not available via NPA. This is notated here.
This is my assumption at first glance and I'm happy to provide additional assistance if this isn't correct.
Sam Shiflett Netskope Solution Architect - North America