Change Host="192.168.5.99" with the remote IP allowed(this is of course more secure but also cumbersome if your IP changes). You could also have a single layer of protection that specifies the IP via firewall or both (of course both are far mor secure).
UPDATE user SET Host="192.168.5.99" where Host="localhost"
or for any/wildcard
UPDATE user SET Host="%" where Host="localhost&qu........