I'm a new Gigabit Fios Internet subscriber. I have to say, I was a bit perplexed with the differences, sometimes quite large, between the official Fios speed test site vs. others, such as Ookla, Google speed test, Speakeasy speed test, or even using xfinity speed tests.
I find that you have to be cautious of using other speed testing sites or apps, because depending on the server that the site or app chooses, this can turn out to make a huge impact in the speed test results.
Also, if you believe you're not obtaining the full upload or download speed, then unplugging your router, waiting a minute, then plugging it back in typically works to increase performance back to normal. One should restart them Fios routers/extenders either by restarting via the app (if allowed), or by simply unplugging them, waiting a minute, and then plugging them back in - it has worked in my experience with Fios, even as I'm a new customer!
Plus, I can tell you for a fact that other speed test sites can vary quite a lot. For example, just minutes ago, I used Ookla, and had absolute horrible results, even as I changed servers a couple of times, but when I used Google speed test, it gave me expected speed results according to my Gigabit Fios speeds!
I was not a believer at first, but now I am, as I've seen it with my own eyes!!
If you are trying various speed tests, and not obtaining even close to the speed you are paying for, then I'd say, use at lease 5-6 different speed sites or apps, and change the servers several times in those sites or apps. If it continues, then restart your Fios router and extender(s), if you have extenders, and then test again, and I'm sure it will solve 99% of issues reported on these forums! Please try this before calling or chatting with Verizon as there's no need to use any more of your time to try to fix an issue that can be fixed by following the above strategy!
Also, I do find the Fios speed test site to be the most reliable and I like the fact that Fios speed test not only analyzes your client (iPhone, Laptop/computer, other device), but also it tests the connection speed between the ONT installed at your residence/dwelling to their Fios network!
So far I am satisfied with Verizon Fios Gigabit speed internet - I am a new customer. If i have any more experiences to share or any suggestions to help out a fellow customer, I'll continue to post them to the forums!
Happy Fios surfing!