Ports not building due to release not supported

Hi,

I am unable to build ports as I am getting the error message –
Ports Collection support for your FreeBSD version has ended, and no ports are
guaranteed to build on this system. Please upgrade to a supported release.

But my version is 
FreeBSD rpi2 11.0-CURRENT FreeBSD 11.0-CURRENT #0 r293851: Fri Jan 22 22:09:32 NZDT 2016     mark_at_raspberryPI:/usr/home/mark/crochet-master/work/obj/arm.armv6/usr/src/sys/RPI2  arm

When I try to update I get the following –
root_at_rpi2:/usr/ports/net/freeradius3 # freebsd-update fetch
src component not installed, skipped
Looking up update.FreeBSD.org mirrors... 4 mirrors found.
Fetching public key from update4.freebsd.org... failed.
Fetching public key from update5.freebsd.org... failed.
Fetching public key from update6.freebsd.org... failed.
Fetching public key from update3.freebsd.org... failed.
No mirrors remaining, giving up.

This version was originally built on FreeBSD 10.2, but I updated it to 11 a few weeks after I got it working.

Any assistance will be appreciated.

Thanks

Mark