Evening from here, I'm a player from the EU who's mainly active in the NA Crystal server (Most of my friends are there after all). I too have the issue of package loss after the patch update to 6.3. Never had it before until now... especially since I have "good" connection from my place to the Crystal Servers and didn't run into any problems prior to the patch rollout.

Dc'd like 7 times today during The Tam-Tara Deepcroft (The 2nd 4-man Dungeon you ever get into) when I simply wanted to do my daily Duty Roulette to level up the Paladin Tank class! Even over world wise can I feel package losses and lag spikes, like it takes a lttile while for my character to load in if I teleport from Old Gridania to North Shroud for example. Sometimes my character doesn't load in at all and it simply dc's me from the position I was in. The issue's really frustrating since I am in love with the game and the friendly community in it!

Did all the same things KhevanFarstryder did too, got no package loss between the fiber and the router and from the router over LAN cable to my PC... even updated my network's firmware and on top of that exchanged my old LAN Cable with a new one in case it was that but it wasn't the issue. Friends told me to try out VPN, which doesn't work for me, then check if the Antivirus program could be the case (Using Avira here) but it wasn't the issue either. I'm honestly at my wits end regarding problems one can fix on their own so it only can be a fault on their end... let's hope they can fix it.