I recently (sunday) upgraded to Gigabit Internet, but my speed is still in the 150Mb range down, and 5Mb up. I rebooted the modem several times, and the computer.
Support basically had me reboot everything, then said they couldn't help because I own my modem (he kept saying he didn't have the "codes" to make changes to my modem).
They did offer to send a technician, but said there would be a charge of $70, so I'm hoping somone here (maybe someone from xfinity) might have some ideas.
I'm currently plugged directly into the modem (ARRIS SB6190), so it's not anyting in between.
You can't get gigabit service with that modem. It's only DOCSIS 3.0 capable. You need a DOCSIS 3.1 capable modem,
I followed advice from:
And the support person this time was extrememly helpful, and reprovisioned the modem - and though I don't get gigabit, the speed more than doubled, and he explained I wouldn't get full speed until the modem was replaced.
If it's not DOCSIS 3.1 capable, it defaults to using a slower speed configuration file. They will only deliver gigabit speeds over a DOCSIS 3.1 / OFDM modulated / PLC downstream channel.