just did those changes, i also tried to disable wi-fi B and see if it could connect to A and it did btw, but then when i enable wi-fi-B, wi-fi a gets disabled and B stays in a weird state of --dBm and no info whatsoever, on interfaces it all looks good except for wwan (wi-fi b) that says Network device is not present
edit: another thing I've noticed is that the moment i enable the second wifi, the one this router creates aka wi-fi b, wwan/wlan0/wi-fi a disappears from the devices page. i think this may very well be a limitation of broadcom then, sadly, it seems it's all the Spanish ISPs like though oof. Is ther a way to bypass this maybe using relayd or some other extra software? if not i guess i'll give up and find a better use for this piece of e-waste tbh
edit2:
tried disabling wi-fi a and enabling wi-fi b, i can see on my phone its working, so then i tried to add another access point with a different name, it breaks again even the wi-fi led turns off (i forgot to mention but this happens too when i tried the wi-fi a +wi-fi b thing from earlier), so yeah i think by now its 100% a limitation, i guess i can just hope that over time maybe some of the developers are able to add support for several APs or there's a way to bypass it somehow, thanks for all the help and sorry to have waster both of your time. at least now i know i wasnt messing up big time its just that the thing can't do it