It's Congestion. You'll see the guy's that arent complaining as much is in area's that have other solutions available (ADSL , Fiber).
Take a look the test that were done by the MYBB Team , The area's where they did the speedtest are all fiber rich area's . I mean Midstream , They have more fiber providers available than we have rain towers.
So a good test like myself and
@cavedog did . Take your device as close as possible to the tower your latched onto and the run the tests again . Try and run it more or less the same times as when you have been running them.
In my case , i have probably spent in excess of 40 hours moving my device around my property. This includes indoors and outdoors.At one point i had 3 X poles joined to see if i could better my connection elevating it above any obstructions , That was about +13m elevation.
I have 3 towers close to me 2 that are completely useless , if i get a solid 6Mbps i'm lucky .
The tower i am currently connected to gives me 10 - 20Mbps during the day and 350Mbps+ from around 01:30 - 06:15 . 4G and 5G not connecting to the same towers , where i am they are in complete opposite directions of each other and about 3km's appart.
To give you an idea , This is over 5 day's and a test is run every 30 min.
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That's my 5c worth.