Dude @alb777
As I know they don't use any system on their boards ... they depend only on modem drivers ... each modem has own drivers installed on it by manufacture
OpenWrt is not driver free
All of them same speeds ... because as I mentioned they are doing copy & paste with some editing based on their requirements and targets
I advise you to buy Fibocom FM190W (X75) 5G/4G ---> long use ...price approximately 280$
if you can't pay this amount then go with Quectel RM520 (X62) 5G/4G ---- around 100$
Note:
RM521-F abandoned on place as per Quectel .. they mentioned on their website ( no more support for it )
Board :
- if you are looking for high speeds . better to go with Driver free board
like this one ...
Aliexpress (Best Board)
if you are looking to have apps and a good add-on on home network better to go with openwrt with Banana BPI-R4
Finally : OpenWrt (Team / Developers) need to adjust system root & network to let system use all core functionally
-
OpenWrt with solution
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Driver Free ( Download Speed is similar to Openwork ---- upload is better on Driver free board .... i think on OpenWrt there is a root for upload need to be assigned to all CPUs)
At end : i'm Mechanical Engineer I don't have experience with programing or other things but I like to find solution for issues ... i'm sure there are a better people .they can do a better solution than me with full details with roots to main source