Hi Peter and Lee,
The pi 3 is working fine with the latest software once I received the new license key - just to confirm.
On the pi 2 I was using the following wifi dongle:
https://store.netgate.com/Pluggable-USB-20-80211n-wireless-adapter-P2573.aspx. On closer inspection I can see the casing to the dongle is cracked and i think this has been caused by it being stressed whilst located alongside the USB's for the GPS or antennae fittings das there is little spacing. It's possible it may have been damaged although it still seems to connect to the internet when the kids are using it. Switching to the pi 3 with inbuilt wifi is a major advantage that has avoided this issue (as you previiously mentioned).
Lee - I can send the wifi dongle but I'd need to first replace it as the kids don't have wired internet access in the room where I have the pi 2 set up. I may shortly upgrade it to a pi 4 anyway in which case I would happily forward onto you so you can inspect it if you wanted to.
Peter - I tried a fresh install of 20190621 and reinstall the original license key on the pi 2 but the license still shows as expired.
Please let me know if you'd like any more info or other tests to be carried out.
Thanks,
Matt