Getting List Merge Error

[Papapooch]

So we tried List Merge for the first time. Did not work. The lists are in identical format, as they were Nth from the same Base List. there are no duplicates in the 2 lists. Is there some setting that can fix this? Thanks

 

[twisted1919]

That's the web server that times out, so the best thing you can do si to alter nginx configuration and add a higher timeout value for connections.
Here's some tips: https://www.scalescale.com/tips/nginx/504-gateway-time-out-using-nginx/