@Wilcar 

Here are some suggestions:

1. Make sure they are compatible with your current Controller version

2. EAP use 5G network to build Mesh network, so set them to the same 5G channel band for a test.

Some countries limited outdoor product in some specific channel range, it might make indoor EAP and outdoor EAP in different channels and cannot find each other.

@Wilcar 

Hi, can you adopt that EAP with a cable? Adopt it then unplug it, this EAP status should turn to isolated. And we can link it manually.

Can you access this page and send us a pic of all your EAPs(after adopt this indoor one with cable)? So we can check the model, hardware, firmware etc.

Dear @Wilcar,

Wilcar wrote

I have another eap that I want to mesh with one of the wired eap225 indoor, but the controller never recognize that, even if put them very close.

I'm using the Omada Controller v.3.2.14, I've already tried to update both the EAP to every possible version but it never come up, I've also tried to mesh the same eap to the outdoor one and there it works, any suggestions?

What's the hardware and firmware version of your indoor EAP225?

Kind note that the current EAP225 V3 firmware listed on the TP-Link website is almost for Omada Controller V4 or above.

To work with Omada Controller v3.2.14, you may refer to this post to get the firmware of your EAP225.

If your concern is resolved, I'd encourage you to give feedback to the community so others can be confident of the solution.