ImtiazAli wrote

@Wally11 Remove the virgin hub & set up the decos again

@ImtiazAli 

This is not the best recommendation for the person with limited IT knowledge. You must know that Virgin hub 3 is modem+router, and just removing it will terminate Internet connection. That person might not.

@Wally11 

I am assuming you still have Virgin Hub3 router and your old computer connected to it wirelessly. You also still have Deco mesh running in your house. 

With these assumptions, as a first step I would recommend to switch Deco to Access Point mode. In that mode, Deco will provide WiFi coverage all over your house, but not interfere with network management Virgin hub 3 is responsible for.

To make that change, open Deco app, and under More/Advanced you'll see this screen where you should change Operating Mode to Access Point:

To continue with troubleshooting, I have a question in regard to your Smart TV(s). Do you have just one Smart TV and it is (was) connected to hub3 by Ethernet cable, or do you have two Smart TVs: one connected by Ethernet cable and one you want to have connected wirelessly?

Also, your Virgin Hub 3 has 4 Ethernet ports. You said you needed to connect Smart TV to Main Deco second port. You should be able to, but why won't you use one of other three Ethernet ports - are they not available? What is connected to them?

@Alexandre. 

Thank you so much for your response. Very clear and helpful. Yes, your assumptions are correct. Yes, I have just one Smart TV and it was connected to hub3 by Ethernet cable. The reason I didn't put it back in the back of the Hub was that my husband said he had read somewhere no to put in any other devices if the Deco was connected to Hub, but he knows even less than me! I will try both your suggestions - thank you.

@Wally11 

Your husband is not wrong, but what he had read applies to different Deco configuration, not the one you have or going to have under my guidance.

You can connect Smart TV by Ethernet cable to any available yellow colored Ethernet port of your Virgin hub 3. It should work, and this is also the test to see if your Virgin hub 3 configured the way I think it is. 

Then, change Deco configuration the way I described. This will simplify Deco setup and will save you from many headaches in the future.

When these two steps are completed successfully, the next step will be to review options for your old PC with WiFi 2.4GHz band. 

After PC is dealt with, the last step, unless you'll have any other issues or questions, will be to decide if WiFi on Virgin hub 3 needs to be turned off. 

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If everything goes according to the plan, no other configuration changes will be required for Virgin hub 3, and of course you would not need to redo Deco set up process again. In fact, as you could see, you are very close to completion of Deco deployment, just few steps left, which I listed, to finish it.