We signed up for the a CenturyLink fiber trial in December. This is fiber to the house. They provided a stock CL modem that hooked up via ethernet to their optical network terminal. This is a single point ethernet breakout which provides their IP based television service as well standard data connectivity.
First, we didn't care about the TV service but it was cheaper to go with it as part of the bundle. It never worked. This was never resolved, but not the reason we switched back to comcast.
We popped for the 100Mbs connectivity. The fiber can deliver up to 1Gbs. It's limited based purely on what you pay for.
I tested using multiple speed testing sites as well as iperf to dedicated servers, etc. Speeds were HIGHLY variable. Most of the time we were seeing real throughput of around 60-70Mbs. I could live with that if it weren't for the video issues detailed below.
For the first several days I saw random slow downs where effective bandwidth would be SUB 10Mbs. Rebooting the ONT fiber termination unit usually fixed this. After multiple days of calls to service department this apparently was either eventually addressed or resolved. No details were provided but speeds effectively stabilized near 100Mbs (never at, but close).
When the service was running well, during the mornings Youtube would STREAM in 4k. This is pretty wild and was impressive. However outside of that sweet spot in the morning, it was buffering city. Even worse: EVERY DAY at around 6pm to 9pm we'd see video streaming quality drop off a cliff, across the board. Youtube, for one example, would auto negotiate to 240p. ON FIBER. EVERY DAY OF THE NEAR MONTH WE HAD THE SERVICE.
While my first thoughts were that they are competing with online streaming to sell bundled TV and thus traffic shaping was a likely candidate, it could also be that they just screwed up some traffic optimization/shaping to ensure QOS for their video service. There are other possible reasons but whatever it ultimately was that caused the problem, my repeated calls to customer service were fruitless.
Literally every call seemed to be escalated to wildly different departments. "you are on the tv bundle? you have to talk to the tv team" (the tv team in a totally different facility). The endless cycles of "it's probably your wifi, after having repeatedly explained to the most senior techs I could get ahold of via the phone, that I am not testing with wifi, I'm hardlined all the way to the fiber, etc. etc.
So after a month, I called, cancelled the service trial and they sent me a box to return the modem, etc. I boxed it up, dropped it off at UPS, checked in with my account to see that it was successfully closed out and that was that. Shutting down the trial was the easiest part of the whole thing.
Until five months later they sent an out of the blue bill for equipment that had "never been receieved". I asked them to check the UPS label associated with my account. I'd actually kept the UPS receipt for a month, but by this time I'd tossed it. After another week of calling UPS, talking to CL customer service and even hoofing it to the UPS to see if they could dig up the information, I gave in and paid for the already returned equipment. Why? I didn't want a collection notice on my credit history, which is spotless. I'm sure most people faced with this either pay like I did or end up dealing with a collection agent. Maybe someone will successfully sue CL for this scam in the future. (OH and the really ridiculous thing: they had a record of the MODEM being returned, but not the TV box, which was of course in the same return box).
So if you do a Centurylink trial, be SURE to either return the gear in person and get (and KEEP) a receipt, or keep the UPS shipping information so you can prove receipt... though even then, I don't know what you'd do if they claim that, say, something was missing in the box, or whatever.