Just to wrap up this thread - Alexey had no problem with my UK PPTP connection with my parameters but Israeli DLink were unable to get a connection. Changing the router to a Dlink DIR-615 K2 with 1.0.14 firmware solved the problem. Alexey suggests that the Realtek processor that the M1 uses (the K2 uses Broadcom) may have some feature that stops it doing PPTP connections outside Russia.