As of a couple of months ago, I play on a satellite connection. Which means I have a 1,700ms ping. I obviously don't expect too much with that much of a latency, but in general, ffxiv handles it pretty well. Except for fishing. Here is the only two scenarios that ever happen when I fish:
80% of the time
You feel a nibble/bite.
> jig
You have hooked something but can't reel it in.
> try again
The fish got away.
20% of the time
You feel a nibble/bite.
> jig
You have caught xxx.
If I don't catch it on the very first jig, I lose my catch 100% of the time. 100%, no exaggeration. I never, ever get "The fish is taking line", "The fish is taking a great deal of line", "You have caught xxx", "You lost what felt like xxx", or "The fish is tired but you can not reel it in". I get bites just fine, but I haven't seen any of those messages on this connection in months. I have exhausted every possibility trying to fix this -- gear, stats, waiting (for several weeks) for any possible fatigue to wear off, bait, trying lower grade spots, whatever. The only difference between when I could fish fine, and now, is my connection. My only conclusion is that there is something about having a 1800ms ping that breaks fishing.