Critical bug ? can this become more specific...
DMM version always mention what type of bug they fixed, like when Serra AW skill didn't heal the party.
Or major exploit on Hana event.
Saying critical bug is more like an excuse nowday specialy when player already in serius disatisfaction.
As for accessing the DMM aigis, yes they are IP block.
To bypass this you need to add stuff in source data for google chrome or just use vpn
Kancolle Command center help to patch this and its where most ppl use.
PS: this just me abit ranting.
Because nutaku gave my friend (ok now he just being unggrateful) sybilla / Nanally in his premum summon, when i introduce him to DMM a week ago he is way too demanding now even though he got black soldier and broken platinum Uzume.
He made a total of 87 acc trying to get Broken black unit and now quit both ver. (his Altair + uzume acc become mine + 1 more unused account with black omyou mikoto)
It felt the failing in EN version also effected the disatisfaction ppl of starting over in JP ver, even though that guy used to get really hooked up to aigis EN ver ( soo much that its tiresome answering all his question -.-)