I had planned to post the following on the Mediacom Support forums, but was unable to register an account after triple-checking my e-mail address and requesting a new verification e-mail 5 times over the course of an hour. So I'm posting this here for public view:
I signed up for Mediacom service around 6 months ago. Once the setup was complete, service was flawless until early December.
Starting around December 3, we started experiencing sporadic packet loss, most noticeable during online gaming and watching videos online. The connection would drop for 2-5 seconds then resume. This resulted in "rubberbanding" in first-person shooter games like Team Fortress 2, where my character would freeze then reappear 20 steps back from where he started.
I decided to buy a new router for $50, hoping it would resolve the issue. It didn't. I had the same issue on both routers.
The problem gradually grew more severe, so I called Mediacom and they sent out a tech.
The tech said the levels were off, so they would send a second tech out to adjust the levels. I heard nothing back from Mediacom for 3 days, so I called back.
I learned then that the second tech had come out (I received no follow-up call or e-mail when the second tech came and went) and adjusted the levels. Unfortunately, the second tech did not resolve the issue. I scheduled a third tech to come out.
While waiting for the appointment, the issue grew worse. At one point, the connection would occasionally drop completely until I called Mediacom and used the automated system to restart the modem and restore service. Turning the cable modem and router off and back on did not resolve the issue.
I later discovered that the cable modem was reporting T3 and T4 timeout errors. I checked the MAC addresses referenced in the logs and discovered one address belonged to my cable modem and the other belonged to a company that sells ISP head equipment.
The third tech came out, checked the levels, checked what he could check on site, replaced some fittings, and things were better–for a while. Then the issue returned again.
I replaced the network cable connecting the cable modem to the router with a known good cable. The issue persisted.
I purchased a second cable modem a Zoom 5341J, for $70 (my first, a Motorola/Arris Surfboard 6141, cost $90) but didn't immediately install it when I received it because the problem subsided for a while.
Unfortunately, the issue returned yesterday (1/6/16). I installed the Zoom modem last night, called Mediacom to provision the new modem, got back online, and went to bed shortly after.
I discovered today that replacing the cable modem did not resolve the issue. The new modem, out of the box for less than 48 hours, is reporting the exact same errors (T3 and T4) as the first modem.
I have now spent $120 in additional equipment to fix an issue that all evidence suggests is the fault of Mediacom. I have spent hours upon hours troubleshooting an issue that has persisted, albeit sporadically, for the last month.
I had AT&T U-Verse Internet for years and the U-Verse service was rock solid for almost the entire duration. (The only reason I left is because they refused to offer a reasonable price for service.)
I am nearly at my wit's end with this issue and strongly considering returning to U-Verse, even if it means paying more, because Mediacom and AT&T have a duopoly on Internet service where I live.
My wife and I use our Internet service for wi-fi calling (Republic Wireless and, soon, Google Project Fi). It's one thing for a game to lag once in a while or a web page to fail to load. It's quite another for us to be unable to drop phone calls or not even receive calls because our Internet service has dropped while we're not constantly paying attention to ping tests.
I really liked Mediacom's service when it was stable. Signing up was easy and, even though it took several calls to get Mediacom to honor the original deal and remove the cable modem rental from my monthly bill, customer service was polite and helpful (eventually).
But I pay too much for a service that has proven so unreliable. Considering the lengths I've gone through to identify and troubleshoot the issue, I don't think it's unreasonable for Mediacom to escalate this issue and provide at least a partial refund on service.