Dungeon Finder Results in Consistent 90k errors

I've been playing FFXIV since 1.0 and jumped back in for 2.0

For the most part i have had no issues, through launch and all the way up to 50 in ARR completeing the story and enough DF roulette to get DL gear.

A few months ago I started to get 90k error disconnection on regular intervals upon entering a Dungeon Finder Group.

I connect to Gungnir, through the JP data centres from Brisbane, Australia with Iinet as my ISP.

I am able to play solo/overworld maps with no related issues, even in dense player areas such as the cities. As of posting I have been logged in, active doing the Easter event with no lag or connectivity issues.

On entering a DF group though I will, without warning stop receiving data, while still sending, all PC's and Mobs will freeze in place and I will shortly be disconnected from the dungeon, placed back into the title screen and able to log in once my character is 'booted' from the world for disconnecting. This occurs around 5 minutes in but usually before 10 minutes have passed. As a rough estimate around the point before the first boss in most dungeons, or just after in rare cases.

I have attempted two separate tunnelling services to address any potential routing issues, am on a new install on a formatted computer, and have attempted different methods of connection to my router.

The random cut from receiving Data only affects ARR and does not affect and services running in the background (Streaming, other downloads) and I have run a connectivity test to confirm my internet is stable.

I am tempted to try a NA server transfer to see if it solves it, but I;d rather stick with my FC and the fatser JP servers. I also fear it is an issue with DF and I would be paying just to confirm that and I would have to unsub as I cannot progress my character any further without being able to run content that is stable.

Any help is appreciated.

Regards

Arken Shini of Gungnir.