@Datalink So it finally stayed down long enough for me to snag the numbers. I have attached 2 images, one right after reboot and the other during the outage, what do you think? 
@PhilP you have cable signal level problems, which probably doesn't come as any surprise. Your modem has two Orthogonal Frequency Division Multiplex (OFDM) channels running on the downstream side and one Orthogonal Division Frequency Multiple Access (OFDMA) channel running on the upstream side. That probably puts the majority of the modem's data on those channels. I won't comment on the signal levels for those channels other than to say that they shouldn't be too far off of the downstream and upstream QAM channel levels. There isn't enough information in the signal level data from the modem to properly assess the health of the OFDM or OFDMA channels. However, if you look at the QAM signal level chart below, one of the downstream OFDM channels is running within that initial runup to 11 dBmV, which won't do it any good.
The QAM channels are much easier to understand and diagnose at this point. So, with that in mind, here's a chart of the downstream QAM channels (1 to 32) after the reboot. One of the moderators will have to approve the image so that its available for public viewing:
Those channels should be running at 0 dBmV, at the bottom of the chart, not ranging up to 11 dbmV. Those signal levels are in a range where customers typically experience modem performance issues. So, that's not good, in terms of the downstream performance. Modems are designed to run within a downstream envelope ranging from -15 dBmV to +15dBmV. After a few years of observation of Rogers modems, if you're outside or +/- 6/7 dBmV, you can expect to have problems, which is where the majority of those QAM levels are running. Typical downstream levels are 0 dBmV with a signal to noise ratio in a 36 to 40 dB range.
The upstream side is also higher than it should be. Typically those upstream QAM levels should be in a 36 to 40 dBmV range. Your's are ranging up to 51 dBmV. DOCSIS specs call for a maximum of 51 dBmV for three or four channel upstream operation. Rogers uses 52 dBmV for some reason. At that point the modem should start to shut down individual upstream channels in order to stay within its maximum power output envelope. I wouldn't be surprised to see some fluctuation between an operation and degraded upstream state. If a channel is shut down, you would notice it as the downstream and upstream data rates will drop. So, you're upstream OFDMA levels will be elevated as well as the QAM levels.
One point of interest is the discrepancy between the downstream and upstream levels. Typically in a cable signal level issue, external cable degradation causes signal losses outside of that external cable. That causes the downstream signal levels to drop and forces the upstream levels up as the Cable Modem Termination System (CMTS) commands the modem to run higher upstream levels so that the upstream data actually reaches the CMTS. Your signal levels are elevated in both downstream and upstream cases. That's an odd combination which shouldn't happen under normal signal level conditions.
Another interesting point is the uncorrected errors in the first signal level chart. That might be ok, or unacceptable depending on how long the modem had been running at that point. If we're talking many days or possibly weeks, then those numbers might be ok, but, if those numbers were captured shortly after a modem reboot, I'd say that there's a noise issue on the go as well.
In short, you need a tech to sort out the signal levels. Switching to an Ignite XB6, XB7 or XB8 will not solve this problem. This is a cable signal issue problem. I absolutely do not recommend switching to an Ignite modem unless and until the signal levels are brought back to within acceptable levels.
Having said that, here's couple of questions:
1. Are you running other services such as multiple Nextboxes and Home Phone service. If so, that implies the possibility of a signal amplifier connected to the incoming cable. If so, signal amplifiers will hide poor inbound signal levels until their seriously degraded.
2. Can you have a look at the inbound cable, where it connects to the house cable system. Do you have a powered amplifier or possibly a passive splitter installed at that location. The powered amplifier is the most probable answer.
3. Would you happen to know when the external cable was replaced, and does it arrive via overhead path from the nearest utility pole, or is it underground, arriving from a local tap (green pedestal) which you can probably see from your front steps? I'm assuming that you're in a house.
If you have a powered amplifier installed, there should be one port marked as a VOIP port. The modem cable should be connected to that port as its an unamplified port. There is a signal drop instead, as that port is an output port from internal splitter. So, you end up with a 3.5 dB signal drop, but, there is no distortion of the output, compared to the amplified ports. The other port of that internal splitter feeds the amplifier section.
When the ignite modems are installed, all of the Nextboxes are removed, the Home Phone modem is removed and the modem itself is replaced with an XB6, XB7, or XB8 modem, which does everything, internet, tv and Home Phone. Any amplifier or splitters are removed and replaced with an F-81 connector which looks like this:
https://www.homedepot.ca/product/ideal-3ghz-f-splice-adapter-10-pack-/1000751479
In the case where the existing modem was connected to an amplified port, removing the amplifier would result in the new modem (XB6, XB7, XB8) showing the real signal levels which I would expect to be much worse.
In the case where there was a splitter installed, removing the splitter and replacing it with an F-81 connector would or should result in improved signal levels for the new modem.
In all cases, removing an amplifier or splitter and replacing it with an F-81 connector will not improve the state of the external cable, so you would still need a tech.
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