How to change colo to bangkok

I try to call
https://uat.smart-niti.com/cdn-cgi/trace
I got colo = SIN why it does not point to bkk which I use server on Huawei (thai datacenter)
fl=35f738
h=uat.smart-niti.com
ip=2403:6200:88a2:df70:351a:5d5e:58d7:e295
ts=1622463430.768
visit_scheme=https
uag=Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.212 Safari/537.36
colo=SIN
http=http/3
loc=TH
tls=TLSv1.3
sni=plaintext
warp=off
gateway=off

Hello,

Thank you for answer
Current I use pro package, Could you please give the document ?

(client ->ISP → cloudflare ->WebServer All is in BKK except cloudflare)
almost client are in BKK but it detect to outside BKK,
It does not make sense, because ISP limit outside our country

If I can’t fix I can’t use cloudflare because internet bandwidth limit very slow.
I send query 3000 query in 1 time take time 10 mins for cloudflare which usually 2-3 mins
It’s very bad experience.