I always see people rip on Mediacom Tech that the internet sucks and is always down. Yes, sometimes there can be issues with the cable going to your home but what I have found, helping friends and myself, is that the Mediacom modems are usually good for about a year to 2 years before issues start.
When to know when your modem is starting to have issues.
1) It will just start randomly going down once in a while, for no reason.
2) It will progressively get worse and happens most when you are using a lot of data. (Gaming, streaming)
3) It gets to the point that you just do not have internet.
When this starts to happen, I just go to my local Mediacom office and grab a new modem from them. Another way around this is buy a modem from your favorite retailer. However with this, make sure it will work with your internet service. Read reviews. This can save you a little bit of money on your Mediacom service but you are on the hook when your modem dies over just being able to exchange for a replacement.
Another cause that I have seen for this is splitters. Just like modems, they go bad. Takes a lot longer for a splitter to fail, but it does happen.
Last, reason I have found to have connectivity issues is the cable end that plugs into your modem. What a lot of people think is that the coper wire connects to something in the modem. It don't. The copper wire, in reality, does not have the signal come through it. It is more like a train track. The signal "floats" around the wire riding it like a track. Now, if your coax that hooks up to your modem has not been properly trimmed, your modem will pick up the signal but it will be weak because the signal just keeps riding the wire into the nothingness of your modem. When our service was first hooked up, we had this issue. Talked to some co-workers at my job, he told me to come home and check out my wire and it was in fact, long., It stuck out from the end of my connector by about 3/16 to about 1/4 of an inch. I cut it back down to around 1/16th of an inch to 1/8th of an inch past the end of the connector and to this day I am still using this same cable, 10 years later, but have gone through about 9 modems in that same time span.
I am on the 1gig plan and hit 975 Mbps down and 63 Mbps up. I know when my modem starts to go bad because that is when I start to have service issues. Otherwise when people in my town post "man Mediacom is just pure trash, my service is out again!" I respond that my service is working fine and there are no outages. Then I give them this very same advice as I wrote here, and then you do not hear a thing from them again.
Being in tech support, I always try and easy fix first. Check your power cord if your computer does not turn on or in this case, replace the modem. If you are renting from Mediacom, it costs you nothing but a little time to go into a local office and exchange. If it does not work after that, then yeah a Tech may have to come to your home and look for other issues.
Now this is my experience and take what I wrote with a grain of salt. My issues could be way different then your issues but I thought I would share my experiences.