change localhost to 127.0.0.1 which should help with ipv6

server-ce/nginx/sharelatex.conf

@@ -5,7 +5,7 @@ server {
 	set $static_path /var/www/sharelatex/web/public;
 
 	location / {
-		proxy_pass http://localhost:3000;
+		proxy_pass http://127.0.0.1:3000;
 		proxy_http_version 1.1;
 		proxy_set_header Upgrade $http_upgrade;
 		proxy_set_header Connection "upgrade";
@@ -17,7 +17,7 @@ server {
 	}
 	
 	location /socket.io {
-		proxy_pass http://localhost:3026;
+		proxy_pass http://127.0.0.1:3026;
 		proxy_http_version 1.1;
 		proxy_set_header Upgrade $http_upgrade;
 		proxy_set_header Connection "upgrade";