Ok, Netgear cannot help you. They do not provide firmware for the CM1200.
even if you did get the firmware upgrade somehow, docsis allows spectrum to downgrade it to their approved firmware and they would have downgraded it back to v1. But they have recently started sending out the good firmware.
Any glitches are because of congestion , spectrum providing a very old firmware that cannot do ODFMA. and spectrum trying to use OFDMA now
Now leave the CM1200 connected, and Spectrum are now sending out updated firmware to CM1200’s to make them OFDMA compatible, and work better during congestion.
You can call spectrum and ask their engineers to check you will get firmware Version 3.02.01. on your CM1200 ,in your area ? It should have been there last week. How long do you have to leave it connected to be sure the firmware is sent through