Smart Hub 2 assigns IPv6 IP address

[bratman91]

For months, I have connected my iMac with Catalina to the internet using BT Powerline adapters and a Smart Hub 2. Just lately, the connection shows only an IPv6 IP address and I have not found a way to connect using an IPv4 one. I have tried all the options detailed in various Apple forums (such as turning off IPv6 in network preferences) and all I can get is either an IPv6 one assigned or, when turning off IPv6, a connection but a self-assigned IP address with no internet. I have tried turning off and on the router. I am starting to think that the problem is not with my iMac but with the Smart Hub 2. any suggestions?

[ptrduffy]

Have you checked that your Hub has DHCP enabled?

It's in Advanced Settings -> My Network -> IPv4 Configuration

[bratman91]

Thanks for your response. Yes, I have checked and DHCP is enabled.

[ptrduffy]

I guess you could rule out a Hub issue if you have other devices that are correctly getting an IPv4 address issued by DHCP - are you able to check this?

Also, I know you mentioned you've turned off IPv6 in System Preferences, but have you confirmed that it's set to use DHCP for IPv4?  On my MacBook running Ventura, there's a drop down called "Configure IPv4" where one of the options is "Unsing DHCP".

There's also button in System Preferences to "Renew DHCP Lease" - what happens when you try that?

And finally, what happens if you set "Configure IPv4" to "Manually" and give the Mac an IP address that's in your subnet but outside the DHCP address range - does it get connected than?

[bratman91]

That’s a good point, ptrduffy,  about other devices connected to the hub. I have two smart TVs connected via powerline adapters and a variety of iPads and iPhones connected by wifi and all of them work fine. My iMac also connects properly via wifi - it is just by ethernet to a powerline adapter that has a problem.

My iMac is in a garden office where the wifi signal is a bit flaky, hence my preference to use ethernet/powerline if possible.

I would agree with you that all this tends to rule out a hub issue but my iMac is over 10 years old and I doubt that it has any compatibility with IPv6 or anything that might indicate to the hub that it needs an IPv6 IP address. The insistence of the hub in assigning an IPv6 address seems odd.

I have renewed the DHCP lease but to no avail.

Tomorrow, I’ll dig out my olde Macbook Pro with High Sierra and see if the issue remains. I do not rule out a problem with the powerline adapter either so I’ll swap it for one that I know works. 

I’ll also try your suggestion about configuring the IPv4 manually once I have ruled out the hub and/or powerline adapter.

Very many thanks for your suggestions - they are much appreciated.

[bratman91]

For ptrduffy,

        I logged into the iMac this morning and, low and behold, an IP4 IP address had been assigned although the speed was very, very low.

        I swapped the powerline adapter for a known good one and, after a few minutes, an IP4 IP address was assigned but, again, speed was very low.

       I tried both powerline adapters with a different mac and the same thing happened. 
          
        I now think that the problem lies with the electrical cable from the powerline adapter master to the slave adapter. I might just have to live with this!

[ptrduffy]

Yes, it sounds very much like the iMac is having trouble reaching the Hub - I would guess that the IPv6 address you were seeing is self-assigned, and was a bit of a red herring.

I don't have any personal experience of powerline adapters, but what I've read on here and elsewhere suggests they're a bit hit and miss - is there no options to run an ethernet cable from hub to iMac?

In the absence of that option, I've found the BT WiFi discs really help with coverage - I have two of them, and they provide a solid signal throughout a fairly large flat with solid brick internal walls.

[bratman91]

Someone on these forums called powerline adapters “the spawn of the Devil” and I have certainly had mixed results from them. The distance and position of my garden office make an ethernet cable very impractical but I’ll try the BT discs solution. Many thanks for all your suggestions.