So, currently my main I play is a WHM, and I love'im to death. The only problem is that, my current connection to the internet is quite sub-par then what i would like it to be, and there isn't anything I can do about it for 2 more months. It causes me to lag out alot, but I've managed to play through up until now, with minimal problems, minus ghosting x3

I'm still playing through the story line and I've gotten to the point where I have to run Stone Vigil. I'm used to running dungeons and they've actually started to really grow on me but the thing is, I got that quest over a week ago, and I have yet to successfully complete it yet. The very first one I did, was through DF. We all get ready and after the first group of trash mobs, both the tank and one of the DPS just stop, and leave the group, followed by the last DPS, leaving me there alone. I got some new randoms about, 5-10 minutes later. We continue on and before we get to the first boss, the tank just leaves and the DPS say to just leave and try it again, It'll be easier then to find a random tank to join. I do and about 20 minutes later, I get my new party. this one runs a bit more smoothly, but again, before we get to the first boss, Tank just ups and leaves, followed by the DPS.

Having that happen twice in a row,got me a bit down thinking my connection was bad and my healing wasn't good. So I figured I try again tomorrow. The next day, I get on and get a party with duty finder instantly. We run through and everything is going great. No body leaves, and everyone is sympathetic towards my lagging issue. They gave me tips on the bosses and told me about the run. Everything was going great... until we get to the end. everything went great until I started to lag. the whole screen stops and I'm just there spamming heal on the tank when next thing i knew, the boss was doing his spam AOE from the sky and everyone but the BLM was dead. They asked I was good and I apologized for the lag. they understood and we went again, this time I didn't laga drop, but we still got wiped. They gave me more tips and we did it again... and again, until we had about 5 minutes left when we all left the group.

This went on for the next five days were I tried running it with members of my FC and some people I had met online. I just feel so bad that I can't get it done, like I'm letting everyone in the party down. I'm trying as hard as I can but even when I get no lag at all, I either end up getting killed because if the stupid aoe, or I get interrupted when I try to heal the tank and they end up dying. i feel like I'm failing as a healer, and that makes me upset because healing is usually the one thing I'm good at in games xD
And If I can't even do a level 41 dungeon, how am I suppose to do anything at end game? Let alone beat the damn thing. I love playing this game and really don't want to wait 2 months to play it again but I feel like I'm not good enough to play as a WHM.

Is there anything I can do? I mean, I know the lag issue is gonna be hard but, is there really just something I'm missing maybe? Is my gear not good enough? Should I try it as another class(would that even count? xD)

I just don't know what to do Dx