I just met a strange case when I use my router in Indonesia. 5G is not discoverred.
After a lot of testing I noticed that the reason is my iPhone is not detecting 5G wifi using band 36 to 60. It only detect 5G channel 149 to 161. The reason is that in Indonesia before 2019 only 149 to 161 band can be used for 5G wifi. So my iPhone is still working using the regulation before 2019 so it will not detect any 5G wifi out side of channel 149 to 161.