@CDRichards 

You might find this easier to setup via the web interface / GUI rather than the App, especially as you can see the log files etc.

What username did you add for the connection and yes it should be set as MER..

Ive only done this a few times but got it working with the generic details, however I know people who have had to extract their SKY specific username nad password.  This link below might help you

https://www.georgebuckingham.com/sky-fibre-router-vdsl-password/

Definately log into the router via the web interface to do this, look in the logs for CHAP or username / password issues.    Any issues post a screenshot in here for us to take a look, as much as you can would help