STO doesn't seem to have any alternate method of client download to Pando at the moment. I've had to install Pando, get STO client, uninstall Pando and then do registry cleaning manually to remove all Pando traces so far.

It's weird that your ISP would filter out a whole range of port for a frequently used delivery software. More than likely, the traffic is blocked by your hardware router/modem/firewall or software firewall/security suite. If you are tech savvy and are willing to fiddle with your PC, here's what you can try at your own RISK: Once you install the Pando installer(the STO online installer will do it.) Do a registry search for "Pando" and look under global open ports branch for at least two Pando entries to find the port that your specific installation is using. The entries should be for UDP and TCP. (Pando ports vary depending on version, installation and what's available on your machine, but seem to stay above the 50K range.) Add the Pando related ports into your hardware/software's firewall/router/security suite's Access Control List (ACL), allow incoming and outgoing UDP and TCP traffic on those ports and you should be good to go. I would recommend that you restore your access control lists, remove Pando software and all of its related registry entries immediately after you get the full STO client. Until they get another download method up, this may be your only option.

IMPORTANT
*I do not speak for PWE or Cryptic support, please send in a support ticket instead if you are unsure about any of the above steps.
**When you uninstall Pando, the uninstaller does not remove the top tier program folders, bugsplat uptime tracker entries and global open ports entries in your registry as well as a misplaced "low rights elevation policy" set for Internet Explorer and/or Pando plugin for Firefox. (The firefox plugin will be disabled but not removed.)