@Alexandre. hello there, touching base again. Ordered XE75 Pro, 3 nodes and Amazon Prime delivered this afternoon. Done the setup but very extremely disappointed due to 

1) Speed is very very slow, not sure why, only 160 - 180Mbs (please note with VM Hub 5, at least I am getting 300Mbps, and with wired 1gb). 
2) From one floor to 2nd, it takes time to join mesh even though I have enabled the Roaming
3) I cannot use as "Access Mode" as it gives an error, saying unable to set as "Access Mode". (please note, I have turned off VM Hub 5 wifi)

I will try to note down the entire error message and send it over to you. 

Also, upon setting, app system asked, what type of Internet connection my ISP, I could not find it on the Virgin Media website so I just picked up the first option "Dynamic IP". Its very surprising, I watched dozens of Deco set-up videos, and not even one video mentioned this part, where we have to select the "Type of Internet Connection".

Thanks.

  @Which_Port 

Usually, initial setup goes much smoother. On setup, Deco will ask you for connection type, because it starts as a router. Dynamic IP is a correct choice in your case, because in your case Main Deco gets its IP address from Virgin Hub 5.

I am concerned with inability to switch Deco mesh to Access Point mode. Deco mesh configuration settings are kept in TP-Link Deco cloud, if you can't change this setting it could mean something may be wrong with your account in that cloud. While you can run Deco mesh in router mode, who knows what other configuration settings you won't be able to set or change when you need to.

I also seen errors when change is made in Deco settings while previous change has not been commited in TP-Link cloud. When that happens, current change is rejected.

Try this: power off Deco mesh, all nodes. Wait for about 10 minutes. Power them on starting with Main Deco. When all units are back on and shown as online in Deco app, try switching Deco mesh to AP mode again.

If that does not work, wait overnight and try again. If that does not work, you'll really have to make a decision: escalate to TP-Link Support or just send Deco back to Amazon. In any case, if this problem is not resolved before return window closes - you should just send Deco back to Amazon.

Your speed test numbers, for both Hub 5 and Deco, surprise me. On gigabit Internet and with WiFi 5 Deco I am getting up to 650Mbps from Main Deco when standing near it. With WiFi 6, which is Hub 5 and XE75 Pro, I would expect speeds close to gigabit. The fact that you can only get 300Mbps from Hub 5 make me ask how do you run speed tests?

  @Which_Port 

Which_Port wrote

  @Alexandre. ok, I think I am all set now. Look, I have no words for your help. amazing. 

Alexander, touching base again. I tried everything but its not converting to Access Mode. I turn off the power and tried several time but this is the msg I am getting.

We Couldn't find Deco.

Something went wrong with the Cloud service. Please try again

If you are still unsuccessful after several attempts, connect to your Deco's wifi network and then try again. 

what shall I do next ? I think I have to have AP Mode. If I am on the G Floor, where is the main Deco, the speed I can see 300Mbps, and if I get to the 2nd floor, the speed is only 96Kb but after a while when the phone connects to the nearest Deco on the 2nd Floor, then the spend better to around 280Mbps. 

so, seems I must need AP Mode so the devices can connect to the nearest Deco asap. 

  @Which_Port 

There are steps to troubleshoot WiFi speed and roaming, but there is no point trying that if you don't have basic functionality, which is switching Deco mesh ot AP mode. Let's focus on that, and if you are still not successful, you'll need to escalate to TP-Link Support or return Deco hardware and go with different brand of WiFi mesh.

I would suggest you reset your Deco mesh network and start anew. 

Here is the process:

1. Make sure all Deco units, Satellite and Main, are powered on and shown as online in Deco app. This is important.

2. Make sure smartphone that has Deco app on does not use VPN.

3. Delete (reset) your Deco mesh by following Scenario 2 from this document: https://www.tp-link.com/en/support/faq/3353/

4. Power off Main Deco and all Satellite Deco.

5. Power on Main Deco only.

6. Create new Deco mesh network with different SSID and with Main Deco only. You'll have to configure it from scratch, choose connection method (Dynamic IP), etc.

7. When you see new Main Deco in your new network in Deco app as online, try switching it to AP mode. Switching a Deco to Access Point (AP) Mode

8a. That does work, Deco mesh is on AP mode - power on Satellite Deco and add them to Deco mesh if they don't add themselves automatically.

8b. You can't switch Deco mesh to AP mode - escalate to TP-Link support or return hardware.

Escalation to TP-Link support from UK: https://www.tp-link.com/uk/support/contact-technical-support/#E-mail-Support

  @Which_Port ok, thank you dear. I am a bit confused. Contacted with TP-Link support and also Virgin Media Support and here is the answer of both parties, which very confusing

Virgin Media Support
Must change the Hub to Model Mode to connect 3rd Party Mesh system, otherwise, all smart devices will not work properly as there will be 2 wifi networks in the property and they will clash. 

 

TP-Link Support
Don't change the Hub 5 to Modem Mode, keep it in Router mode (which you said it also), and then make the main Deco to Access Point Mode and after set up, still keep the VM Hub in Router mode. I tried but still no success. TP-Link just say sorry and requested to file a complaint about this. 

So, now the only option, I will follow your above step and let's see.