"Harry Bloomfield" wrote in message
news
I have just this week moved to fibre (well VDSL), from ADSL. On ADSL I was
connecting at 18Mbs, speedtest at around fairly consistent 16Mbs.

I was moved in the early hours of Tuesday morning, since when speedtest
results have been all over the place - sometimes 31Mbs, sometimes 10Mbs.
My initial tests showed a steady, 30Mbs with the ISP supplied dumbed down
router.

I bought a second identicle router, but with OpenWRT installed. I spent
much of Tuesday trying to gets it configuration settings to work, swapping
to that and back to the ISP router, between times, until I finally got the
OpenWRT to work - so multiple times.

Throughout, a connect speed was reported of a steady 40,000Mbs/9.000Mbs,

So the service is fine.

yet actual speedtests showed wild variations.

That's normal, it varys with the server its using.

Are the wild variations part of the system settling in

Nope.

and how long might it go on for?

Forever. Speedtest is a lousy way to measure performance.

And its important to measure it over a wired connection,
not over wifi. Wifi just adds another variable.