Strange IPv4 problems after Full Fibre Upgrade

[WSH]

Strange indeed.

It sounds suspiciously as though the Wi-Fi extender has its own DHCP.  That wouldn't cause a problem until it just happens to allocate an address that the hub has already allocated to something else.  Quite often in that situation, the network grinds to a halt while the two devices argue.   If it does have a separate DHCP, there will be a management interface for it on the Wi-Fi extender.  I'd go into it and turn off the DHCP, if I were you.

[paulwt]

I connected to the WiFi extender and it does have a DHCP setting.   Currently it is set to automatic with alternative options of On and also Off.     If I set it to off will that not prevent devices connecting to it?

[WSH]

Ah, that will just be for where it gets an IP address from.  Leave that on.

I was talking about an second DHCP, issuing addresses to other devices.

Under the circumstances RBZ5416 would seem to be right.  It sounds like MAC Randomisation on  mobile devices.  The idea was to protect you from tracking by issuing a new MAC address everytime the device connected.  The trouble is DHCP will see it as a new device each time and issue a new IP addresss, eventually running out.  The hub then needs a factory reset to clear it.  I'd turn off MAC randomisation on your phones etc., as it was really intended for privacy on public hotspots.  In the real world, it's a nice idea on paper and a pain in the ... on domestic networks.  Unless you are really paranoid about tracking, turn it off on each device.

You've not got half a dozen kids with smart phones have you?  That will soon use up the available addresses.  LOL.

[rbz5416]

W11 also has MAC randomisation that should also be turned off.

[WSH]

Good point but not necessarily, it would seem.

I've just check my 3 year old Win 11 Pro laptop and that setting is not there.  I suspect it depends on the capabilities/age of the network card.  Mine's only 802.11ac.

[rbz5416]

@WSH 

Odd, my Lenovo is four years old, also with ac. I thought it was baked into Windows rather than hardware dependent.

https://support.microsoft.com/en-gb/windows/how-to-use-random-hardware-addresses-in-windows-ac58de34...

[WSH]

Very odd?

I've never seen it on Win 11 but I'm mostly a hardwired man anyway, so the whole Wi-Fi thing is usually not there.  I suppose it's implementation is inevitable if other manufacturers are doing it but it's definitely not present on my Acer X515EA.

Just for reference, is that setting on or off by default?

[paulwt]

I can turn the MAC randomisation off.   However, I did do a hard reset of the hub and it didn't clear the problem.   I also had the hub replaced and the new one immediately started to exhibit the problem.   However, restarting the WiFi extender does seem to have cleared the problem.    To clarify the extender had been in for a number of years with no problems and the continued to work throughout.   The Smart hub also worked fine until the switch over to full fibre when it started to exhibit the IPv4 problem.   I am pleased the problem has gone away and if it returns I will just restart the extender again but not really sure why it occured and whether it was just a coincidence that it happened at the same time as the fibre switch.

[WSH]

Yes, it’s a strange one.

With changing/restarting something like the hub it is possible that it confused the extender and it retained the old network settings, causing a clash.  Those sorts of problems don’t always happen with a restart but I have come across similar before.  It can be a good idea to restart the other network devices after the hub has been restarted.  I take it you restarted the hub and then the extender after the new ONT was up?

Sorry, at this point, I’m out of ideas.  If it works now, I suggest you just see how it goes.

[rbz5416]

@WSH 

I believe it was on by default as I recall switching it off. But if it is indeed hardware dependent, then I guess it could be up to the hardware manufacturer to make that choice?