Really strange result with EE. Utterly bazar, Ive used their services before and I could consistently pull close to 70-80mbps on 4G and this is even during peak hours. Throttling could mean them capping at 20-40mbps but 3.91 is extremely extremely poor.
Obviously a tonne of factors can affect performance. 3.91 is pretty much akin to Three network and their 4G speeds most of the time lmao. If the reception is great but youre suffering from poor speeds then either the network is throttling or the device itself is possibly a little faulty such buggy firmware reporting full reception when it really isnt or limiting its network speeds (could even be a configuration issue - Ive worked with other netgear, TP-Link and Huawei 4g router devices that didnt have the right ISP profile settings so had to manually entered into the config)
Another suggestion would be to wait till 1am before running the speedtest.net test because thats when usage is really off peak and networks unlock their limiters.
I was an EE Mobile BB customer for almost a year and while i was a Three MBB customer for a lot lot longer. One of the best days of my life was when i left Three for EE....
Or maybe its because i live in a central part of the UK which means that they got all their big hardware down here and because BT being BT have all the infrastructure in the world to keep speeds running at close to regular broadband speeds...
Strange.