Cable modem event log

I upgraded to a 1 Gig connection late last year. Never looked at the logs until a few days ago.

I only see ATDMA(QAM). Do you see any data for OFDMA? Also, your downstream levels look high. They should be +10 to -10dB. Are you going through a coax amplifier? If so, I wonder if that is causing the problem. 

I only see ATDMA. I remember a tech plugging in an AC Adaptor to one of the outlets in one of the rooms and connecting a coax cable to it. Model: YS16F-1500500. Anti-lightning surge voltage: 6KV. It has a warning: Cable TV/Internet Service. Do not Disconnect. This could be an attempt to condition/amplify the signal coming to the coax cables in the house from the outside. What is the better alternative if I want to upgrade to a 2-Gig connection down the road? Rewire the entire house?

Not the entire house, but the coax between the pole and modem, yes. That is a power supply for a amp. Amps can cause issues with speeds, specailly upload. How is the coax wired in your house? Why do you need a amp? Do you have a lot of TV boxes in the house? If not, I suggest running a coax from the street/pole directly to the modem and get rid of the amp. 

BTW, I am not even sure how you are getting 1Gbps without OFDM or OFDMA. What does a speed test show? I doubt 2Gbps is available in your area without that signal. That is the whole purpose of DOCSIS 3.1. What model modem do you have?

I found OFDM and OFDMA data:

I have 3 mini cable boxes in use throughout the house. Only one has a splitter (an Antronix CMCDT2109TC-A) connecting to the modem: Netgear CM1200. The modem gives me on average 875.63 Mbps download and 111.42 Mbps upload using an Ethernet connection.

Each room has it own cable connector/wire, but not all connectors are active. Only the ones that are in use are active: I think about 4 or 5. Maybe the coax wiring in the house is not that good. Could a fiber connection for the modem improve things? And leave the coax wires for the cable boxes/TVs? I hope getting a 2-Gig connection does not make things worse.