Although myself have a Rogers CGN3ACSMR modem/router, my question is more generic and not related to any particular make/model.
Although my modem/router has no issues, I have the habit of rebooting it once a week, my reasoning being to allow its software to finish installing any background firmware push by Rogers (if any).
My questions are:
a) is it a good thing ?
This is just my opinion: I would argue that a reboot (especially if you power-cycle your modem) is a good thing to do from time to time because it resets the hardware and software into a good state. However, it should not be something that you must do.
b) is it necessary to reboot modem/router once in a while (weekly or monthly) even if no issues at all ?
No. And I would also argue that it's also a good thing to leave it running for an extended period of time. If you do not experience any issues, it gives you added confidence that all is well.
However, if you must reboot your modem frequently to keep things stable, then that's definitely not good.
c) does the weekly/monthly reboot harm the modem/router in any way ?
It should not. The one downside to a reboot is that is also clears stats that the modem accumulates as it is running. I don't know how often Rogers polls the modems for a status check, so rebooting too frequently may give them a false indicator of how your service is actually performing. They get most of their trend data from the local node/CMTS, so your modem's stats are only a small part of what they see but it does provide them with indicators of how your service is working from your unique perspective.
I tend to let my modem run for weeks at a time and do not restart it unless there is a network glitch that requires me to do so.
However, if I see my uncorrectable codeword errors spike, I'll watch the error counters closer. If my line performance starts trending badly, I'll call Rogers and have them investigate. If line conditions appear to have stabilized, then I'll power-cycle the modem to reset the stats.
Re: firmware updates, my modem gets updated in the middle of the night and then reboots itself, and that's usually how I know that my modem's firmware got updated. I have never been able to get firmware fixes (that I have been waiting for) any faster by rebooting. I have only received them only when Rogers pushes them out.