AP500 don't have UPnP, always the router have this feature. I would advise that you don't use C7 as an AP, just let it be router and AP500 relay its wireless network.

Thanks for your advice. But this is not an option. The provider wants us to use his cabelmodem HITRON CV30360. I could bridge it but that would stop phoneservices. In fact i tested it, but this was also slowing down the hole network (only 30-50MBit/s instead of 100MBit/s. Five users sharing about 10 to 15 devices).
I know that the AP has no UPnP-Option. The question was: DOES the AP500 BLOCK the ports????? And if it does, why? Is there an option (firmware) to get it functional like other devices (e.g. Asus).
I want to cover not a little home but the hole property and every floor. The best way to do so, is using APs or do you know a better one?

yours, NoTrouble (with troubles)

I think AP500 is the best product of the TPLINK AP. From the words you said AP500 can work with cable modem, just with low speed. I think it is normal for the first, and the wireless speed would be lower that cable speed when wireless speed influenced by many factors. Ok, go back to this, AP wouldn't block any ports and you also need to open ports from C7. See this FAQ: http://www.tp-link.com/en/faq-72.html. you could also find the UPnP option and you need to know which port you want to open then you could enable that port by yourself.
If you still have problem, i think you could contact our hotline: http://www.tp-link.com/en/support-contact.html.
Or you could submit the ticket here: http://ticket.tp-link.com/index.php?/Tickets/Submit.

I agree - the AP500 is one of the best products of TP-Link. The new surface of the software is really clear and easy (not working in all aspects yet - e.g. switching from 2.4 to 5GHz).
But nevertheless my AVOX Internetradio gets no connection with the NAS through this AP. So I sent it back for I'm now using another AP (which works - even without the C7, that has the UPnP activated).

It's not at all you said: the AP500 can work with cable modem, but with full speed (100MBits/s, intern NAS/PC up to 400MBits/s). Slowing down speed was a result of bridging the modem.

Thank you for your help.