Speed dropped by a quarter over the last month.

[licquorice]

Each time you restart either your router or ONT, you can expect your IP address will change, that is normal behaviour.

[Sadgepogs]

Okay, cool. Thanks guys for clearing it up. 🙂 Odd that it didn't used to change my client location.

[ptrduffy]

So there is no fault at all that my client location and IP address change frequently? Where as before it was fixed location?

"client location" as shown by fast.com is a guess based on your IP address - and so can change when your IP address changes (e.g. after a Hub or ONT restart as others have said).

I suspect this type of complaint will become much more common as more people migrate to FTTP, resulting in more contention on local PON infrastructure.  Most people just don't realise the amount of sharing going on, and the impact that could have on their speed at any given point of time.