Splashtop Gateway supports importing your own certificate, which can be self signed certificate, or certificate issued by 3rd party authority.
PKCS#12 (PFX) format certificate is supported by Splashtop Gateway.
Step 1. To import new certificate, please login to Splashtop Gateway's management console as the system admin, and go to System > Security page. It shows the current imported certificate information, if there is no certificate info shown, it means Gateway is using the Gateway bundled self signed certificate.
Step 2. Click Import, it will show the importing dialog, select the PFX file and also the password which is set when generating the certificate.
Step 3. Click Import to finish importing, which will restart Gateway service to make the new certificate effective.
References: