Bit of a strange one, recently had FTTC enabled on my line, to which im making use of a RJ11 extension from the back of the master socket (using the filtered output). Using my Billion 8800NL its showing a Max Rate of 49mbit, however when plugging directly into the Mk3 BT Openreach master socket downstairs I only get a max rate of 45mbit. This doesn't bother me in the slightest as I would rather use the extension, I just thought it was a little strange thats all! Line is stable using the extension with minimal errors, averaging 8 ES/hour.
Does anyone know why this might be?