Having the same issues when playing Black Desert Online! After looking at my WinMTR logs, the BDO support team told me that my ping and latency were equivalent to what they would expect to see from someone playing in Australia! Just as the user above me reported, all of my other internet use was unaffected--I can stream netflix, play other games that connect to the internet, and browse, all without any lag. When I run connection speed tests, everything comes back as normal. Apparently the WinMTR logs show that this is not the case for when I am running BDO.
Please resolve this issue which seems to be affecting may BDO players, and seemingly only those who have Cox as their isp.
