2.4 and 5.0 mhz connections

I have an XB7 router/modem.

I have 4 pods.

I have several devices that are on either 2.4 or 5.0

I have talked with a great support lady, who tried to help me (for neatly 1 hour), but could not help me in the end.

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My question  is :  since we know that both frequencies are working properly, why is it that some devices

(some that specify requiring 2.4) and others that apparently use 2.4 but not specifically required, refuse to connect.

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I just returned a bridge and extender that would not connect.  I have three mini cameras that won't connect.

I have in the past year or so also returned several devices that would/could not  connect.

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I have several new ioT devices that I was surprised to find (on the support call) were connected via 2.4.

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Now can someone explain to me what is going on and how to fix it?

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Also, support lady suggested that I could disable 5.0 in the router admin, for a short time, thus 'forcing' the

2.4 device to connect, then re-enable the 5.0 in the router.  She did warn not to leave it disabled too long

 to not affect the connected 5.0 devices.   But, I am pretty wary of doing this.

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I'd like to  add that I am a retired IT professional, so will understand any technical info/advice given.

thank you for your help. any and all help appreciated

ds

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