I tried various formats in /etc/config/wireless, like
option ssid '"\31\66\36\30\32"'
option ssid 3166363032

which should work according to orig basic hostapd.conf

But, no success.
Any help here ?

Just as a general remark, characters beyond the printable set of 7-bit ASCII is a recipe for disaster, as different interpretations among different operating systems and implementations are bound to happen (in the case of emojis even up to the problem of font support on your clients).

While hostapd.conf does correctly treat the SSID as binary, the escaping from the config files is interpreted by UCI, shell (to generate the temporary hostapd.conf) and even your browser (when entering it), which introduces quite some margin of breakage among these different entities here as well.

First paragraph ACKed, as I am very well aware of it.
Second does not provide any help at all, but only confirms the very bad,
modern (open source ?) style, to assume, the user first of all has to dig into the functionalities of underlying software, to figure out, how to use an other wise very well documented interface.
Although off-topic, this is one more example, that openwrt might better adhere to established, well documented procedures (here: functionality of hostapd.conf) instead of introducing some nebulous processing (uci, shell etc.) which reduces this functionality.

I think this is an operating system problem, because the os has to interprete the numbers as an emoji.

Instead of ranting about unproven facts, maybe simply try it out first? I copy-pasted "Smiling Face With Smiling Eyes" from here https://emojipedia.org/smiling-face-with-smiling-eyes/ into the SSID field of LuCI which led to the following output:

In "cat /etc/config/wireless" it rendered as:

And a network survey on an iPhone yielded this:

So you jump to conclusions and rage about nebulous processing without ever actually trying to copy-paste the emoji into the SSID field?

(Last edited by jow on 8 Jan 2018, 15:34)

Not using LuCi. I copied the respective line from /etc/config/wireless in my post.
As I wrote already.
And you might read org hostapd.conf regarding valid ssid formats.
Before doing some wrong assumptions.

But to clarify, you might post the contents of /etc/config/wireless after using LuCi successfully.
Which might give some serious insights.

(Last edited by augustus_meyer on 8 Jan 2018, 16:40)

The valid SSID formats you've been trying to use are defined for the `ssid2` option of hostapd.conf, not the `ssid` option which is mapped by OpenWrt.

For the contents of /etc/config/wireless refer to the screenshot above.