If you require a serial number, we recommend using RazorX's PSO Tool GUI program to generate one. It is recommended to not use a shared serial.
For the NTE and Protoype versions of PSO, use any serial number generated from the above for compatibility with newserv. Make sure it is not a pattern such as 11111111 or ABCDE123.
If you receive an error saying that your access key is invalid, this means your chosen serial number has already been used on the server and the access key you are using does not match. If this serial number is truly your own from a disc or another server, please post on either the forum or Discord regarding this with proof. If not, you will need to change your character's serial, with the instructions at the PSO Tool GUI page.
Note that the NTE and Prototype versions of PSO downloaded from here will automatically connect to Ragol.org, so there is no set up required other than general internet connectivity.