MattNZ wrote

Does DFS relate to this in some manner?  I assume so, in the channels above 5260, or even in the 5480+ zone. 

Yes, it does. An outdoor AP needs to implement DFS/TPC as well as an indoor AP which uses U-NII-2A indoor or U-NII-2C outdoor channels. That's why indoor APs often do not implemet the U-NII-2 band at all (A and C both require DFS/TPC).

Here is a good overview of world-wide 5 GHz frequency allocations and requirements.

Yes, the hardware works extremely well, along with the software if configured correctly, however it would seem prefectly sensible for the wizard at least to have a question relating to channels or 'outdoor', so users who are not fully aware of the technological intricacies can work through to a resolution.

Honestly, I wonder why there is a wizard at all. It's not that difficult to configure a CPE manually. 

There is a note at first login asking for agreement to have Pharos devices only be deployed by a professional, so you can't hold TP-Link responsible if regulatory authorities knock on your door and seize your WiFi equipment because you did run it in Test mode - yes, those inspections happen pro-actively nowadays (at least in continental EU), since interferences caused by abusing frequency bands has become a big problem for commercial and military use of the 5 GHz band. That's also the reason why newer CPE510 V3 models don't let one enable Test mode anymore (what's a pitty if needed to test a link sporadically), albeit the firmware still has it.

TP Link advertise the EAP225 to be indoor and outdoor, but don't lead you down a particular path on your need.  I have only just found the 'channel limit' option in the Omada software, (now that you mention it below, so thanks for that).  I see it won't use channels below 5350.

That's another story: In older Omada controller versions one could enable/disable the channel limit per AP, which makes sense if an EAP225-Outdoor is installed indoors. Someone then had the idea to make the »Channel Limit« option a global option and have the controller apply it to every EAP225-Outdoor automatically. So, you cannot use mixed indoor/outdoor setups of EAP225-Outdoor with the same controller anymore. Bad idea if you ask me.

All units have the latest firmware, and they still perform in the same manner, with 'test-mode' selection required to see the AP's I wish to connect to.  Perhaps if the location is set to countries other than the UK, the channel width is different, however I followed the wizard...... 

The problem is that DFS is required by law, even in U-NII-2A which is used by some indoor APs. Thus, a fixed DFS channel isn't actually fixed, even not in Test mode. In former firmware versions for the CPE510, DFS could be disabled to force a fixed channel, but that option has been removed, too.

Yes, you're right that TP-Link could make it clearer what conditions need to be met in which regions regarding channel limits.

But even the important requirement to properly ground an outdoor CPE is stated very clearly in the Installation Guide and almost nobody obeys or even reads this (that's the reason why you can find many posts here about suddenly broken CPEs or CPEs behaving abnormally after they did run fine for some time - until a heavy lightning storm happens).

My pleasure if you find the informations useful, have fun with your CPE!