For the last few days I have been getting awful ping spikes and sometimes disconnects on BDO rendering it unplayable. This is not happening with any other game nor web browsing. I am at a loss for how I can diagnose the problem when it only manifests on BDO and nowhere else. I cannot afford to pay for a VPN just to see if that would fix it. Does anyone have any suggestions?

My husband and I are having the same problems. I have been unable to horse train for the last few days without the game reloading every few minutes and lagging out on horse capturing so that I lose the captured horse. Other games are fine. Tried all the usual advice, reset the router, verify game files, update graphics driver, restart game and PC etc. Nothing seems to work and the game is unplayable doing anything other than afk fishing which seems to work fine!!

You could try reaching out to your ISP to see if there are any issues they are aware of. Other than the Siege on EU_Mediah_1, I am not aware on any widespread server issues during the weekend

I've been seeing the described above issues too on the EU server, especially while grinding. For a split second mobs just stand still and no hits are registering then all of a sudden the hits register all at once. Other guild members are reporting same issues, and in general/world chat others are also complaining about lag. Our GM stated that PA have acknowledged that something messed up with last patch although I haven't been able to confirm this yet. 

I also get lag when grinding in the normal world, mobs will take around 2-10 second even sometimes up to 30sec-1min to register hits. When grinding in marni realm this doesnt happen at all. I tested my ping connected to blackdesert64.exe and im around 60-120ms so my internet shouldnt be the issue (download & upload speeds ~500mbps). I tested changing my graphic settings from low, med, and high presets and all of them have the same lag. I sit at 60fps most of the time, unless in towns with a lot of players.

edit: upgraded to a samsung 870 evo ssd and it fixed my problem.