You have a hidden network.. that is bad.
In the second screenshot.. hiding the SSID was supposedly a security feature in the early days of wfi.. it was dreamed up by the router manufacturers.. it is not part of the code.. and never has been. In other words all the router manufacturers use it because everyone else does..
1. it is useless. Any hacker can see the ssid. It is clear as a bell in any wifi analyser.
2. it is worse than useless because it breaks some of the way that clients connect.. it causes problem.
I doubt that is the only issue.. but please never bother with hiding ssid (wireless name in applespeak)
Your security level is also lower than it should be. The one and only N wireless rated security is WPA2 Personal (AES to everyone else). If you have old G wireless stuff that doesn't work with WPA2, get a secondary WAP for it to join or use the swisscom router for that.
I would also lock the wireless channels..
On the swisscom set it to 1 and the TC set to 13 or 11 if that is problematic.. USA rules the world when it comes to wifi even if the regulations allow up to 13.. but if it is possible 13 is perhaps the least used channel in the world. Many client drivers cannot work with anything outside US code.
You can try setting 5ghz.. channel but my understanding is that it doesn't actually work. AC wireless uses 80mhz and so needs too much bandwidth.. apple seems to stick to 149.. I am unsure so if you want to report your findings please do.
Test it using the wireless diagnostics software on a computer or an app you can download for ipad/iphone.
Check that the channel is set correctly.
The diagnostics in Mountain Lion / Mavericks is fine.
http://support.apple.com/kb/HT5606
