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Apr 30, 2017 How to Use AirPort Express as a Wi-Fi Extender | Small Open the AirPort utility on a computer that is connected to a network with an AirPort Extreme or … How to Set up Time Capsule to Extend A Wireless Network, 2

Oct 21, 2019

Jun 17, 2019 How to increase your Wi-Fi coverage with an extra AirPort

Yes. The issue was the extender, EX3700, does not play well with Apple AirPort Extreme routers in that the Apple device assigns channels for both frequencies automatically which may not be suitable for the EX3700. Using the Airport utility I assigned a new channel for each frequency. They were 11 and 153 for 2.4 and 5 GHTZ respectively.

Bridge mode on the Extreme will not support what your trying to do. I don't know if AIrport Extreme supports Extender or any Repeater modes. Something to ask Apple about. I would focus on the Orbi, if your having problems with wifi, lets see if we can narrow down whats happening there first, then later on, see if you need an extender.