NeoMod wrote

It's connected as a simple Access Point (PoE) trough a PoE Switch.After a lot of troubles with the Controller Software (honestly, that's a horrible piece of software) I managed to configure the EAP225 to work as an Access Point.

The EAP Controller isn't needed to set up an EAP. Actually, it doesn't even make much sense to use the EAP Controller for setting up a single EAP. You could use the EAP in stand-alone mode and configure it through the web UI if you don't need the extra functionality of the EAP Controller such as its Captive Portal or batch firmware upgrades.

When connected to the Wireless Network form the EAP225 some domains are inacccessible, like when you block them via firewall except there is no firewall on the network and the same domains are accessible when connecting directly via Switch.

All EAPs are operating as data-link level devices, so they just give you the same connectivity wirelessly as is available by wire if directly connected to the switch. I never experienced such problems with the EAP225. Which domains are you using for tests?

NeoMod wrote

The EAP so called stand-alone WEB SERVER did not offer the same personalization level offered through the controller software. (as an example, try to configure a personal image and logo for the guest network portal from the stand-alone web server. It’s not possible).

That's right, the EAPC offers extended functionality for Hotspots such as portal page customization.

I just have set up a brand-new EAP225 with our EAPC and enabled the Hotspot portal (auth scheme: no authentication, i.e. single-click login). After login, I can access Google search results, repubblica.it, ilmattino.it, ilmessaggero.it, feedly.com, TP-Link website/forum, gmail, etc. without any problems. No blocking whatsoever happens. Controller is v 2.4.4.

If you want, I can offer you to temporarily adopt your EAP225 to our EAPC, so you could compare the behavior of your clients with our EAPC if you think that the EAPC is the cause for blocking requests (I can't reproduce this at all).

Another way to find out what happens is to set up your EAP in stand-alone mode with no portal function and just a WPA2 key. Are the sites mentioned above still blocked? If so, it's something in your network. If not, turn on the built-in portal. Still blocked?

Except for management data and the authorization handshake of unauthenticated users, the EAPC does not receive any traffic. It therefore can not filter domain names or even IPs, since all traffic will only flow from client systems through the EAP through your switch directly to the router. So, if the EAP/EAPC can capture user's requests and let users log into the Hotspot, doors are wide open to the Internet w/o any interaction of the EAPC at this point.

What I can imagine are "security provisions" of your admin for the local network, e.g. client authentication using static leases, which could block traffic if not connected to a switch by wire or something. Did you check this already?

Anyway, if you want me to adopt your EAP225 for a test on our Controller, send me a private mail through the forum's mail system.