First of all, this firmware does not allow SSID names to contain spaces, even though a space is a legal character in a SSID name!
Secondly, this firmware only allow the first SSID name to be 31 characters longs, even though the maximum allowed SSID name length is 32 (and the input field even allows 32 characters to be entered in the first place!)
If either case you will get an "Illegal SSID Name!" alert message (the developer could apparently not be bothered to make the message more specific and tell the user WHY the SSID name is supposedly illegal), and you will not be able to add additional SSIDs, or configure these existing SSID's on new access points that have this firmware.
The workaround is to revert back to firmware 188.8.131.52. You can upgrade to 184.108.40.206 after adding the "illegal" SSID names, they will remain after upgrading.
The new firmware does have an interesting new feature: it can download its configuration from a TFTP server (either through DHCP or by specifying the server), but I have not been able to find the documentation on how to get this working.