As expected it was something quite trivial I had my router running with WPA2-PSK (AES) when I switched it to WPA/WPA2-PSK (Mixed Mode), I was able to connect my Raspberry and RecalBox to the WIFI. All good. Sorry for the trouble hope that can help someone else.
Cheers 
G*
I'll just add something quickly my internet provider here in the UK is Sky Broadband and there seems to be other people experiencing issues connecting their Raspberry to a Sky Hub/Router.
G*
Hi All,
Loving RecalBox so big up for putting this together!!! Amazing stuff!
Now unfortunately, I am currently running into a bit of an issue connecting to my WIFI router and I was wondering if someone could give me a few pointers to try and resolve it.
I am in the UK and I am using RecalBox v4.0 on a RaspBerry PI3
I seem unable to connect to my WIFI router, I get the below:
Occasionally I will even get an IPV6 address instead of the standard IP address but sadly the status remains "Not Connected" to my despair... I have tried changing the channel on my router but that basically brought my whole internet connection to its knees.
If I use my Mobile Phone as WIFI hotspot however then no issue at all; see below:
So based on the above I am assuming it's something to do with the configuration of my router.
Is there anything I should be looking out for in the router config? I have yet to try with a wired connection to the router to check. I will do that shortly. In the meantime your help would be much appreciated. I suspect it's probably something fairly silly... but even after reading many posts and checking the config on my router there was nothing obvious that stood out. 
Many thanks in advance,
Guillaume