Valore Frequenza TX Orbi RKB752 e 852

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Fra11 wrote:

It's the last iMac avaible. Airport Extreme doesn not support 802.11AX but 802.11AC up to 1300Mbps but I don't know why with Orbi RKB752 it gets "only" 866Mbps. I thought that wifi speed was up to 1200Mbps.

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"last iMac" isn't a great description, however, it's perfect in line with the substandard information Apple does deliver on thier Wi-Fi clients in place on their products. Luckily, 3rd party references confirm the Airport Extreme 802.11ac up to 1300Mbps - this happens while operating on 3x3 and the highest standard modulation:

From the RBK75x (AX4200) vs. RBK85x (AX6000) specs.

• AX4200 Tri-Band WiFi : 2.4GHz (600Mbps†) + 5GHz (1200Mbps†) for WiFi devices to connect to the Internet. 5GHz (2400Mbps†) dedicated WiFi link for faster data connections between Orbi Router and Orbi Satellite

• AX6000 Tri-Band WiFi : 2.4GHz (1200Mbps†) + 5GHz (2400Mbps†) for WiFi devices to connect to the Internet. 5GHz (1200Mbps†) dedicated WiFi link for faster data connections between Orbi Router and Orbi Satellite

Now, this is almost like Apple specs - but we can recursively figure out what is going on. The "...for WiFi devices to connect to the Internet" is designating the max PHY link speed between the client and the Orbi router or satellite, the so called fronthaul; the dedicated WiFi link does make up the backhaul.

The RBK75x is a marketing-wise stripped down version RBK85x - however it's essentially using the same hardware and WiFi radios - but for a different purpose: The fronthaul and backhaul radios are swapped.

Looking into the 802.11ax side does how this:

The max.1200 Mb/s fronthaul on the RBK75x is made up from a 2x2 radio, while the max. 2401 Mb/s is made up from a 4x4 radio.

Because of the Airport Extreme 802.11ac up to 1300 Mb/s is a 3x3, but the RBK75x is only 2x2, the max 802.11ac link rate to these devices is limited to 866 Mb/s. In recursion, we can assume the same iMac should be able to make the 1300 Mb/s link rate against the RBK85x.

Than you duckware for the always informative reference for explanaitons!

Regards

-Kurt

PS. The transalation "Frequenza TX" is awful - it's about the negotiated PHY link rate. Your provided screenshot helped a lot 8-)