The 7.20.3 was built in 28th October, but we did not want to publicly release it until PPPoE server fix was available. The one major issue a lot of users reported for v7.20. This 7.20.3 version however was needed for a new device for factory installation.
Now that PPPoE server fix is available, we have released both version, the 7.20.4 being the latest stable.