Lost my IP address again today. CS had been due to call me back since it failed yesterday too - but of course they never did.

When I called again, this time their excuse for the constant loss of IP address and necessary CM reboots was that I should be turning the CM off regularly anway, as otherwise it would generate lots of heat!
After I confirmed that they had carried out all their diagnostics I rebooted the CM so it would give me an IP address again - although CS refused to acknowledge that there was a problem, saying that it was the fault f my PC and that I needed to run the cmd:
>
netsh interface ip reset resetlog.txt" each time. They didn't know how to do this on a router, but they didn't support routers anyway...
Then after I talked again to a supervisor, he said that I would have to call again when it stopped working again.
I insisted then that they send out an engineer to examine the CM since that is the only thing that has not been replaced yet - so we'll have to see how it goes tomorrow...
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Quick addendum to this:
I also discovered whilst monitoring the DHCP lease behaviour (for just my PC behind the CM) that sometimes the lease is for an hour, and then after another refresh it goes to 2 days! Anyone else seen this?