[client] Cleanup firewall state on startup (#2768)

client/internal/dns/server.go

@@ -533,6 +533,13 @@ func (s *DefaultServer) upstreamCallbacks(
 			l.Errorf("Failed to apply nameserver deactivation on the host: %v", err)
 		}
 
+		// persist dns state right away
+		ctx, cancel := context.WithTimeout(s.ctx, 3*time.Second)
+		defer cancel()
+		if err := s.stateManager.PersistState(ctx); err != nil {
+			l.Errorf("Failed to persist dns state: %v", err)
+		}
+
 		if runtime.GOOS == "android" && nsGroup.Primary && len(s.hostsDNSHolder.get()) > 0 {
 			s.addHostRootZone()
 		}