ASUS ROG phone 6 256gb 4G+ speeds slow

[BTTman]

Please tell us some basic information before asking for help:
Model Name: Asus ROG phone 6 256gb
Firmware Version: WW_32.2810.2209.197
Rooted or not: Not rooted
Frequency of Occurrence: happens all the time
APP Name & APP Version (If your issue relates to the app):
In addition to information above, please also provide as much details as you can, e.g., using scenario, what troubleshooting you've already done, screenshot, etc.
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I just got new sim card and my old phone s20 ultra beats this phone mobile network speeds by huge marginal!

I have tried to same server for each phone and s20 ultra got nearly 3 times better score with this sim card. Is there something I could do to improve result. Even YouTube struggles to work on mobile network
Also my old sim card worked fine with this phone but not this new one..

[thuggs]

Really hard to trouble shoot with all the different variables. Download an app that tells you what network you are on such as (LTE Discovery) and make sure each phone is on the same network band.
Also it could help to ask your carrier for a re-provision for the phone with the SIM. They will reset the APN and such, i would do this first.

[BTTman]

It is always B3/B20 connection and not B1 as on my old s20 ultra 5G so is this my phone problem or what?

This is my current phone active connection and it is not even connecting to B1 tower...

Edit: also what does CA mean? In my old phone it is just LTE

[FunBike31]

CA = Channel Aggregation
The ROG 6 can 'in theory' simultaneously use 6 frequency bands for download and 2 for upload, specs below
LTE: DL 6CA Cat20 up to 2.0 Gbps / UL 2CA Cat18 up to 211 Mbps
It depends on the need, the country, the operator and the possibilities of the antenna where you are connected and those nearby.
Indicate your country, the operator and you have purchased the phone distributed by asus for your country

[yosef019]

i sugest you open new APN with modern settings
i have in israel old apn settings for Partner company still as Orange with very old APN settings