You can use custom fields online. Just ensure that you don't have more than 5 fielders on the leg side, not more than 2 behind square and finally atleast 4 fielders inside the circle for non- power play overs. Else the fields do not show up in a match. Also, I think straight hit field position is considered as leg side and short third man and short fine leg are considered outside the 30 yard circle.
Anyways, my experience with online gaming has been a mixed bag. Have had some awesome matches (one was yesterday in a T20 where i was 16/7 and from there ended up on 167/9
). Then again I have had some laggy and glitchy ones. Here are the issues I have faced so far:
a) Batsman being bowled (happened twice, both last ball of an over) and yet the game not acknowledging it and quickly shifting to the next over as if the 6th delivery never happened
b) Batsman being given out even though he hit the ball along the ground and was fielded by mid off (happened in the same match as above).
c) My opponent kept throwing the stumps down with his keeper whenever I missed any delivery, and even though I press circle after each delivery the batsman goes inside the crease and then out again due to the animation resulting in a stumping. Happened twice. Though this isn't an online only bug but is more exaggerated online if the opponent is persistent in throwing down every single delivery to the stumps whenever you have missed one.
d) Batting was totally laggy in a couple of matches with fielders suddenly reaching the delivery and throwing the ball even though they were far far far away from the ball just .1 seconds back. Didn't happen in all matches I played though
e) Bowler stopping in his runup when he reaches the crease , turns back, starts walking towards his runup and then suddenly delivers the ball magically (same as what can be seen in the ivg online mp video posted by Sam)