Wizard's Sanctum Mesh (Stormwind)

You need to add UseEvenIfCanFindPath or w/e it's called to the connection.

@Matenia still doesnt work,

var Mash = new List<OffMeshConnection>
        {
            new OffMeshConnection(new List<Vector3>
            {
               new Vector3(-9019.261f, 888.1429f, 29.62084f),
               new Vector3(-9020.968f, 890.6682f, 29.62069f)
            }, (int)ContinentId.Azeroth, OffMeshConnectionType.Bidirectional, true),
        };
        OffMeshConnections.MeshConnection.AddRange(Mash);

you need to add destination position (where portal teleport) (I haven't tested, but you positions seem very near)