Guild Wars 2

Yeah, sorry for that.
For me, vizunah square : european server
For field not known :

0 – 3 -> uint32 ? value == 2 : so, maybe the region like you said, not really certain without more data
8 – 27 -> always 0 ?
32 – 35 -> uint32 ? 5 in pve, 9 cbe, 11 green map, 10 blue map, 12 red map. ?
40 – 43 -> always 0 ?

:edit: correction, for 32-35

byte[4].byte[5].byte[6].byte[7] == ip address of the map/server i think.
/ip in the chat window has the same number.

edit:
byte[44]-byte[47] == uint32 and seems to be the build version of the game (cf https://api.guildwars2.com/v1/build.json)