forrest wrote
But your EAP and router are not managed by the same software, that is, fot the client devices, you still need to input the password when you are roaming between the EAP and router.
@forrest, if the WPA key is saved in the client device, roaming between EAPs and other APs works indeed as defined in 802.11 very early (it's not fast roaming, but it's roaming anyway).
APs use the ESSID (the WLAN name, usually just called SSID) and a BSSID (device ID, its MAC address) to connect to an AP. If the ESSID and credentials/WPA key of all APs are the same, those APs form an Extended Service Set:
Thus, roaming between the APs in the same Extended Service Set works, even among APs of different vendors (but not so if using portal functions of Omada Controller; portal authentication works only among EAPs in an ESS).
@MichaelS: it's always the client device which decides to which AP it connects to (except if you use fast/seamless roaming of Omada Controller and force disconnects, but that's another story). You choose just an ESSID, but the client device looks up the ESSID and chooses the BSS of the AP with the best signal level.
So, if your client device still gets a good signal while on the basement, it won't change the AP at all. This means that the EAP has an excellent coverage. To force your client device to change the AP you have to either manually change the SSID or to move to a place where the signal of the EAP is much weaker than that of the FritzBOX's built-in AP. Likewise, the same occurs if moving from the basement to the 2nd floor. However, the WiFi signal has to fall under a certain signal threshold leevel to cause the client to change the AP automatically.
Since the client device needs to perform a wireless scan when changing the BSS automatically (that's the same if you change it manually by selecting the AP's SSID), you will note a short drop of the connection. If you want to avoid such connection drops, you can use fast roaming such as 802.11k/v which is supported by EAPs, but probably not by the FritzBOX's built-in AP.