For those unlucky enough to be getting merged.
Lost Ark is getting ready for its server mergers that will see 24 servers unceremoniously sutured into 12 on September 28 with another 8 to get the same treatment in the next few weeks. While most servers can expect a four hour downtime with the upcoming maintenance, Amazon has warned that players on merging servers should expect up to 16 hours of downtime.
At the start of downtime, all regions will begin maintenance at the same time. Regions that are not experiencing merges will have an estimated downtime of 4 hours to deploy the new update. Regions that are experiencing merges, however, will experience a downtime that is longer. We are currently estimating that the downtime for regions with merges estimated to take up to 16 hours.
To compensate players, Lost Ark is hosting a two week login event starting from the point where the servers come back online and running until October 12, or very likely delayed to two weeks after all the ensuing server issues are dealt with. Log in every day to get stuff.
Source: Lost Ark Forums