Hi, when creating a Wi-Fi hotspot on the FP4, the set band is ignored. If I set the band to 2.4GHz, the Access point is still operating in the 5GHz band, ignoring the setting.
To reproduce this, just create an access point with a band setting other than dual-band and then check on which channel the AP is operating.
As far as I remember is that because in some countries you are not allowed to run APs in the 5GHz band. @All Please correct me if that is wrong
Yes, regulatory domain is a concern when running an Access Point. I don’t know of any countries that prohibit 5GHz operation, however the restriction is, that devices can’t operate without performing an extensive DFS scan on the channel. Most consumer Wi-Fi devices have the 5GHz channels flagged as no IR (Initiate Radiation) so they will only begin transmitting, after they received a beacon from an access point, which indicates that the channel is clear. The problem here is, that the FP4 hotspot goes to either the 2.4GHz or 5GHz band, ignoring the setting completely. This is probably decided based on available airtime by the Wi-Fi driver and probably selects 5GHz more often, because the 2.4GHz band is an absolute war zone almost everywhere and has less channels.
I thought, it was using 2.4 GHz no matter what you chose in the settings However, I did not test this on my FP4. That would have been a “typical” SW solution for FP-OS in my opinion 
Very late but just for the record, yes, 5 GHz is not allowed (or used not to be allowed) outdoors in many countries. Since the use of mobile phones only indoors cannot be guaranteed, only 2.4 band is / was allowed for hotspots provided by phones.
However, in Europe new rules were published in 2022 relaxing restrictions for certain bands, but that will have come too late for the FP4 and indeed I suspect the FP5 which was released less than a year later [Edit: I just checked, the FP5 provides a 5 GHz hotspot.]
EDIT 2 : I now see that my FP4 is offering a 5 GHz hotspot with the “Dual band” option. Build FP4…TP2N.C.0128.