Hello all. This is a first post for me, and I figured this may be a good place to put it... Anyway, here's the story:
I've always used testmy.net to test my internet speeds ever since discovering it many years ago. I've always had Comcast, and each time they've given me more speed it would show up just fine on testmy.net, no matter how many times, either in a row or over time, that I tested (except for very rare anomalies). Things were always stable. Just recently we went to the comcast office to pay a bill and discuss our data cap (1TB...). Actually, my father went there, so I'm not sure exactly how everything went, but he came back saying "i upgraded the plan for basically the same price, but now we get 600mbps and no data cap -- we just MUST use this new modem". The new modem turned out to be the XB6 (monolithic, odd-looking device they now are calling an xFI gateway or something). Our old device was what they called the XB3, and we were getting 240mbps, which was ALWAYS stable via ethernet. Both devices also provide WiFi, but I'm the only one who doesn't use the WiFi - I ONLY use ethernet (I'm the only PC in the house). Anyway, I plug their mysterious, mandatory modem in and voila! 721.6 mbps! What an improvement! I tested again and again, each time getting roughly 500-700, which I thought was odd since my speed had always been a rock solid # in the past, but I figured it was just due to us now having such a high speed that even a tiny drop during the test would now show up. Either way, I was satisfied.
Fast forward 1-2 weeks. I had been periodically testing the connection since we got this new modem/plan, and even though things seemed stable at the start, I am now getting TOTALLY different results most tests. Anywyere from 5mbps to 760, and all numbers in between. At really off hours it'll show up near 700 on 1 or 2 of the US destinations and also the Toronto one (I'm in Chicago, btw), but Dallas has been getting worse and worse, to the point where now it's almost never showing 600-700 and almost always showing about 100-200 (and it's not uncommon to see <20). Upload speeds are usually fine, as I only get 22-24 with my comcast. During the day, esp prime time, it's much worse and more random across all of the fastest destinations for me. I realize there are TONS of people staying home and using the internet with the whole covid-19 thing , but is this normal for everyone? I mean, super prime time hours never seemed to affect my speed in the past (superbowl, etc). Why would Dallas (by far the best destination for me theoretically and in the past) be giving me such horrible results? Why is my connection showing up so poorly and so randomly when using this site ever since I swapped to this "XB6" modem? Until/unless I can figure this out, I'd much rather just go back to the 240mbps plan if that way my connection is rock solid. Anything more than that is just icing anyway, usually only benefiting me when downloading huge steam games....
Oh, I'd also like to mention that literally every single other test on the internet gives me ~700mbps without fail. Testmy.net is the only one producing these results, but it's the only site I have trusted in the past so (obviously) I don't know what to make of it. I'm sorry for the wall o text, and I thank any of you who do read it all and try and help me. This has been driving me nuts lately.
PS - Here is a link showing the different comcast modems.- https://www.xfinity.com/support/articles/broadband-gateways-userguides
The ones I brought up, the XB6 and the XB3 are 2nd and 3rd from the top. Also, I forgot to mention that after realizing my XB6 came with a "mobile hotspot" that set up a separate wifi network for "anyone with their own comcast plan" to use, I quickly disabled it (even though they said it shouldn't affect our personal network speeds...). No change. If anything, the results (esp Dallas) are even slower.