Are you wanting the IP to change?

No. I was waiting for it to change to swap the router over. It didn't really matter. Just interested to know why it became sticky after weeks of regular changes. Obviously disconnecting the supplied router dropped the connection and caused an IP change.

Interestingly I am now on an Opal Telecom DSL IP, but with soo many ISPs being bought out, you can't really tell a lot from the IP anymore. When I was last with Plusnet I suddenly started getting BT IPs. Obviously Plusnet were/are part of BT, but I think Plusnet did run out of "their own" IPs.

If you don't disconnect the session on a router then theoretically you could keep the address forever. As I said in my first response the address will only normally change if the session is disconnected - the fact yours changed every couple of days before suggests either their was a problem or the ISP was forcing session disconnects for some reason - in the past I have had times where I have had the same IP for months and that is perfectly normal.

I should add, IP lease time is not what you might think it is.

In a LAN the IP lease time is the minimum amount of time an IP would be assigned to the same device. However, periodically the device will go to the server to say "I'm still here, please extend my lease". There is nothing in LAN DHCP that would automatically force a device to get a new IP if the device was working correctly.

ISP IP address assignment works a little differently to LAN DHCP but in essence this is no different - the lease time does not affect how long a device will keep the same IP if it is permanently connected.

It's odd as my router has been on pretty much 24/7 for the last five years and apart from one year where I purchased a static IP as part of one of my Plusnet packages, my IP has changed fairly regularly.

Like I said earlier I am familiar with Sky and Plusnet DLM but not with Shell's system, if indeed there is one.

Yes, I am familiar with requests being, say half of the lease time.

Perhaps I should have titled my post ISP address assignment, but it doesn't have the same "ring" to it.

The comment still stands - lease time makes no difference unless the link disconnects at some level. As I say, what you are seeing is perfectly normal behaviour for a stable connection.

DLM is Dynamic Line Management and is a VDSL2 layer, i.e. nothing to do with the IP layer and also is run by Openreach for VDSL2 services. ISPs have some limited input but the variations are just the changing data meaning DLM behaves slightly differently.

I've a feeling it is the BT Wholesale DLM in question, or may be TalkTalk Business. AIUI the OP is on ADSLx via a Technicolor 582N.

Your comment is of course valid for that too.

I just assumed the DLM would cause the line to drop and hence a change in IP.