Same problem here, about 3 weeks ago. Comcast came to dig up our yard and said it wasn't at our house, the issue. They had 4 other houses to visit in the neighborhood. Yet problem still goes on...getting like 2 mbps down. Same problem whether wired or wifi. My phone is faster.. Hoping to see what you get as a reply to help us have more info too!
I did all of that well before posting here and found those posts as well. My router was throwing those errors as well. Adjusted everything everything on my end possible. Comcast admitted it was on their end. Haven't seen another tech on Monday like they claimed I would. The connection is better but same errors and constant.