Fibre Speeds non existent internationally

Hi All

I'm currently experiencing fibre speed issues. these issues only arrised in the last month

At the moment doing a linetest or even speedtest to a server in New Zealand my speeds are 102Mbps download and 24Mbps upload which is fantastic as my plan is 100/20

But as soon as I check against servers overseas my speed drops to as little at .73Mbps but upload being fine

I have done a full throughput test for Slingshot and got an email back saying there is no issue, but calling them back they said they couldn't find a fault. I've reset the router. flushed DNS. had slingshot fix the dns in the router as it wasn't going anywhere.

there definitely seems like there is a fault as i am unable to download my antivirus program or any other program. i can't update my Ps4

Every time i try and download a program from an international source they connection just times out

I am wanting to upgrade to Windows 10 but can't until i get the international speeds as my antivirus program isn't from NZ

On a separate note when doing a connection on my ps3 and ps4 i get a message at the bottom of the page stating the router doesn't support ip fragmentation. I've been unable to find any decent information about this and am wondering if anyone can shed some light on fixing this