I have an Asus AC68U Router
Ah, that's a combined VDSL Modem/Router, isn't it, that you are using instead if the PN 2-box setup?
Then rebooting it could change the sync speeds.
1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 20 Meg WBC