Basic steps to see if you can improve connection issues:
Also, there have been a number of people recently finding improved performance or connectivity using "Passive; Secure FTP (TSL)" for FTP mode instead of "Passive; Standard". This requires the commissioner changing the setting if it's currently "Passive; Standard", and then providing new accountsdata_gms.dat file to anyone with issues.
The mode should be changed for all options on the Online League FTP Settings. Must close OOTP after changing before copying accountsdata_gms.dat, and any GM trying the file should copy the new file in with OOTP closed.
This mode is compatible, only GMs with issues need try an update.
Some GMs find that forcing OOTP to download with HTTP instead of FTP works better. This can be changed by a GM on their own by first picking "Online League FTP Options" here:
And then on the next dialog checking the "If possible, use HTML instead of FTP...", then hitting "Save and Close"
Note that the downside of forcing HTTP downloads is OOTP cannot check if the league file on the server is new, and it will always download the current league file.