Ok, always worth checking to save wasting hours figuring out the obvious!
Could you access your router using http://192.168.0.1/ or http://192.168.100.1 for modem mode . You shouldn't need log in, select the 'Check Router Status' option and paste your 'Downstream', 'Upstream', and 'Network Log' tabs? Please copy/paste this data as text, split between multiple posts (Sometimes you have to click 'Post' twice due to an error message).
EDIT: Already done the below I see!
Could you please create a BQM (Broadband Quality Monitor) here, and post the live link?