Around 5 or 6pm every day the connection speed listed on my router will drop around 4-5mbp/s.
The speed listed here:

This is consistant on both the included HG630B and my Fritzbox. The speed will remain at the lower speed of ~7 until the modem is rebooted, and only if it is rebooted outside of peak times.
I have had this issue ever since signing up with Spark, but it was much more pronounced before I had a master filter installed.
Is there anything I can do to get this sorted?