OK, have reached stalemate with my new 16S.   

I want to run 3.x plus on Internal, 2.5.2 on external module.

Its operating well with a Namimno external 2.4 ELRS module, two models attached that way, both OK. They are on 2.5.2

Now remove the module, to set up Internal on a model v 3.x with no possibliity for conflict.  

Try to update the 3.x installed to latest stable 3.3.0. It won't flash, fails via WiFi though it connects and identifies the Tx. (but see known issue below) BUT ALSO fails via Passthrough which it says should work.

The reason stated for WiFi fail is that Tx makers are using differing partition sizes and these prevent update.  States to back date to 2.5.2, then run a "repartitioner" utility, then load 3.x and all well.  Well, NO, as it won't even flash 2.5.2!!

Finds and identifies Tx WiFi, but has the yellow triangle in Dev Man.  (Laptop is Win11, STM virtual com driver states not for Win 10 so presume not for 11 either.   Impulse Driver Fixer will not run.

Try to flash internal via passthrough to 2.5.2, fails.

Gave up and went to fly quads via external.  

What am I missing please?

ELRSv3 requires a different partition size than ELRSv2 used, so WiFi updating requires an intermediate step on TX modules. I would recommend you just flash via EdgeTX passthrough following the flashing guide: https://www.expresslrs.org/quick-start/t...assthrough

Even though you are on Win11, download and install the STM VCP drivers as instructed in the flashing guide. The file you want is VCP_V1.5.0_Setup_W7_x64_64bits.exe.

The other issue that trips people up is that ELRSv3 requires a slightly higher hardware baud rate to load the lua than ELRSv2 did. On a TX16S, this can safely be set to 5.25M (default is usually 400k).

Yes, I had followed both texts accurately for Wifi and Passthrough.   It was the STM VCP issue that was stopping it from flashing.  Ignored warning and did it, instantly it all worked

Now corrected, but its worrying when STM's text states NOT to use it beyond Windows 8!!

I now have 3.3.0 on internal and 2.5.2 on external, so should be covered for older SPI and new  

Thanks for help.