Firstly,

Welcome to Malaysia! Where first world aspirations meet third world reality!

By choosing IP, basically we just disconnect and reconnect or reboot our modems and hope we get assigned a good IP address. Not sure about Celcom Broadband but Streamyx users are given dynamic IP addresses (not entirely dynamic since you're given a very limited range of addresses to use). In your case, I'd suggest just trying to disconnect and reconnect your modem. You should be able to see your assigned IP address in the modems' settings menu.

And using a tunnel service has become the norm if not the requirement for WoW players over here. Without it, you'd get what you're currently facing. With a tunnel service, you can get 200-400ms average.
Some areas may be extremely lucky and provide good connection. But for the most part, I think we're all using a tunnel service.

i have been using gamepath for quite sometime now. it is still very slow recently, and infact its even more stable to not use gamepath these few days.

in both case (with gamepath or not using gamepath) 25man content is still unplayable. clearing thrash is ok. but once boss fight starts, ur connection drop like a brick.

i find recently without using gamepath. u can still stay online but lag like hell, i can still do normal uld25 (i cant even do normal mode  with gamepath recently)  but anything demanding like any hardmodes . u will make the group fail due to your lag (low dps/heal/tps, whatever ur assigned to do).

also a note about gamepath:
when i started using it 5 months ago their gateways were very good. But now i guess they wanna make more money, they have been showing signs of overpopulating each of their gateways. the common practice used by most profit minded organisation anyway, i blame the govnmt for failing to enforce business ethics.

its sad seeing ppl who stay in cyberjaya also failing to get good ping haha, i guess my area is hopeless.

what is meaning of cyberjaya? haha cyberlol or cyberphail?

edit:
i used to ge able to get good ping using 60.48.xx.xxx ip. can anyone who have been using this ip give me a good new IP to work with?

one thing that i noticed, though
the latency were good before the conversion to battle.net
i mean good was below 500ms all the time
but after the conversion, recently, the latency shot up to 800ms all the time and never seems to hit below 700ms at all
oh yes, i'm using our national isp streamyx
just my 2 cents

ops, i forgot to add that i got DC-ed quite often, too
though it normally happened when i was trying to login
and not during boss fights or etc, hehe

yea im lagging badly in this two days also
im a streamyx user between..
anyone here experienced the same problem too?