Orbi won't connect with some devices, how to solve? Settings? Attach previous N900 router?

Ok - so there you have it. The burning questions are :
1) is there something obvious that would cause this connection not to work (I don't accept "too high end" as a reason).  Could it really be incompatible?
2) Is there something obvious I can do to potentially make it work as I think it should?
3)If it is indeed incompatible, is it possible to plug my old router into the orbi and and somehow configure it to connect to this dumb ass pool device that apparently can't keep up with technology? Can you please tell me how to do it correctly?I've never extended before by linking routers together and so I am only following instructions - I don't undertand why things need to be a certain way to work, and I am reading on this forum that the orbi wont allow you to use another router as an extender anyway, which is what I am trying to do right?  I don't actually need more coverage, and I don't care if that connection is a little bit slow even - I just want to use it to make my devices work if that is the only way.

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1. Some devices have trouble connecting to Orbi's single-SSID dual-band network. I have two such devices.  One is older and the other is a just-released Android-based product. I had to wire the Android device. The other device I will need to replace.

2. Probably not.

3. Assuming your old router supports "access point" mode, you can plug your old router into Orbi and use it as an access point solely for the purpose of connecting your two problem devices.  In that case, you should use a different SSID than Orbi.  You need to make sure you use different WiFi channels than Orbi uses.  You should also disable 5 Ghz on the old router if your old devices are 2.4 GHz only.