Enabling MESH in an established wireless environment

[Einstein]

Our current 4 year old wireless network has had MESH disabled. We have now installed 2 - MR76's with external ant-23 antenna with the purpose of getting wireless to another building. From what I can see, the ONLY way to do this is to enable MESH to ALL AP's not just the 2, MR76's that will be making this connection. I do not want to simply tick a button that could instantly change our entire wireless network which has been working perfectly for many years. When I see that bandwidth can be affected by 50% !!!, I pump the brakes. 

Could I get some input on this before I proceed. I have read most of the notes from Meraki:

Wireless Mesh Networking - Cisco Meraki

Using a Cisco Meraki Access Point as a Mesh Repeater - Cisco Meraki

Mesh Deployment Guide - Cisco Meraki

Extending the LAN with a Wireless Mesh Link - Cisco Meraki

but still have many unanswered questions.

Thank you all in advance, I really appreciate all the input. 

[JonathanSwitch · Accepted solution]

Enabling mesh should not impact any AP's that already have a wired gateway. Mesh networking only applies to AP's that are not connected to the wired LAN upon which they become repeaters connecting via Mesh to a gateway AP.

[Einstein]

Exactly what I was hoping to hear.  Strange I could not find this simple answer/explanation anywhere in Meraki docs hence my hesitation.  Very possible I missed it?  Thank you very much my friend I appreciate the quick, concise answer, you rock 8-)

[JonathanSwitch]

No problem. I think it's likely due to the fact consumer grade products tend to market "mesh networking" as this sort of performance enhancing wonder-drug technology which muddies the waters of what it actually does in an enterprise network.

[TBHPTL]

Wired WiFi affects available your over the air bandwidth by 50% The whole half duplex thing.....  A single mesh hop will cut that to one half and then another half of that for each hop.  Run the cable or fiber, you will thank me later.

6 GHz will make this much less impactful but no outdoor 6GHz yet... 

[Einstein]

Would love to, ripping up 100yards of parking lot is not in the budget  😉

Just a single hop, should be ok. 

[PhilipDAth]

Turn it on.  I net you don't notice any performance difference on the existing WiFi network.