I am having a recurring problem. At random times, my S33v2 Modem will lose its connection to the internet. No warning, and no clue why it is happening. Power cycling the modem restores its connection, and my ISP cannot detect any problems. I run the modem through an ASUS Wi-Fi Router, and when the connection drops, we still have network access, so I know the router isn’t the issue.
I have looked through a few threads, and have accessed the Web Manager to check the signal power levels. The downstream power levels and SNR levels are within the recommended range.
The upstream power levels however, are within the acceptable range (35 - 50 dBmV) according to my ISP (Xfinity), but NOT within the range suggested by the manufacturer (45 - 51 dBmV).
Picture below.

I have done a hard reset of the modem, via the reset switch on the bottom, but nothing changed.
I am at my wits end with this, because there is no predicting it, and I’d like to avoid buying a new modem if possible. This one still works, and meets our current needs in regards of speed.
Any insight would be much appreciated.