Extremely slow download speeds for at least the past 4 days

Hi, I've been getting download speeds from 1/6 to 1/5 of what they should be the last 4 days since I started running tests to check it.  Normally speedtest.net and speedtest.xfinity.com both show I'm getting at or slightly above the download rate I pay for which is 300 MBps -- upload bandwidth is still normal.  The automated phone menu system at the customer service number reported no issues at my address yesterday, but I did manage to confirm some sort of problem via Xfinity Assistant and was informed that system updates would fix it.  Well after a the text alert yesterday evening saying that the updates were completed I confirmed nothing has changed.  I am currently getting from 50 to 80 Mbps download speeds from speedtest.net and speedtest.xfinity.com.  I had tested with speedtest.net in June and it reported 316 Mbps download speed. 

The problem may have been going on longer than just the past 4 days, but it's now affecting the quality of my work VPN connection (as you know VPN adds more latency, which makes it much worse!).  A tech is scheduled to come out on Friday.