URLFetch["https://theme.npm.edu.tw/exh108/calligraphy"<>"10801"<>"/ch/","StatusCode"]===200

Select[
Range[10800,10000,-1],
Pause[RandomInteger[3]];URLFetch["https://theme.npm.edu.tw/exh108/calligraphy"<>IntegerString[#]<>"/ch/","StatusCode"]===200&,
1
]