@leomuzzi wrote - It does seem to me that the problem is on the device. Any chances you met that problem before?
I haven't seen that problem before within the scope that you are describing, so Im not to sure what's occurring with your speed, could be the Device but as a general rule Huawei do make good and reliable Kit.
You mentioned your swapping the Three Sim with the EE Sim, so first off just concentrate on one issue at a time rather than comparing two different Networks. lets concentrate on the EE Sim for now. Have you been checking the APN Profiles after a Sim Swop or Factory Reset, it should be Automatic but still worth checking that the profiles are correct for EE.
For Huawei and EE I normally set the APN to as follows -
APN - everywhere
Authentication - PAP
IP type - IPV4 Only
Preferred Network Mode - Auto
Networks Search Mode - Auto
Network Roaming - Off
If your doing a Manual Network Selection, you will not see any 5G Networks, only 2, 3 and 4G so select 4G as the 5G Signal sits on top of 4G on SA Network currently. But its best to keep the Network Selection to Auto.
Split the issue into 2 parts for 1, the Radio Modem (4/5G) and 2, the Device WiFi, on the WiFi check you have split the 2.4 and 5ghz Wifi Bands and are using the 5Ghz and the Bandwidth is either set to Max, probably 160Mhz if it has WIFI 6. also check your WiFi Channels are not conflicting with the same Channels in your Area (any good WiFi Tool App will do, I tend to use 'WiFi Analyzer' or 'Network Signal Info' from the App Store). If you can, do a direct Cable connection (Ethernet) to a Lappy or PC so you can work out what your WiFi Speed Loses are (Cable vs WiFi), if not always carry out Speed Test within a Meter or two to the Router (Not Too Close ie next to it as you may lose WiFi MiMo). Once your happy the WiFi is doing its Job then concentrate on the EE Network side.
Try placing the Device in different locations around the Home, Ideally High Up and near a Window, after each move do a restart and wait at least 5+ Mins, if your Device is Unlocked and Firmware Free there should be a Tool within the Admin Page that will assist you for Logging the best Signal Position for your Device when Moving, if not you can download the Huawei AI Life App from the App Store as the App will have a Tool called Find Optimal Location, this App is for External Antenna Installation but will work with the Device being moved indoors, if your Device is a Pro 2 then it probably will not have any External Antenna Ports but if it Has, make sure the Antenna Settings are set to 'Internal or Auto' within the Admin Settings.
By the way your 5G Signal Levels are very Good, but as said the 5G sits on top of the 4G Network so good 4G Signals are just as important.
Try all of the above and report back your findings also do a EE Network Status Check from the EE Site or App, when testing try and make a note of the time of day, 4 and 5G Signal and the CellID (Mast ID) and Speeds.
