You're right. The signal stats looked o/k at that snapshot in time, but the error log entries confirm that something is going on. Perhaps there is noise ingress into the line(s) somewhere.
There are other signal stat figures that can't be read by the modem. They are the "Upstream Rx Power" (Upstream Receive Power Level), the "Upstream SNR Ch." (Upstream Signal To Noise Ratio), and the "Upstream ICFR" (In Channel Frequency Response). These are as equally important in diagnosing connectivity issues as are the modem's stats.
The tech can poll the system for them. See what he has to say when he comes out. Good luck with it !
... View more