If compatibility test fails because UPnP is supported by your router but not enabled by default. You can fix this by logging into your router admin panel and enabling UPnP. For more information take a look at this article:
If your router is old and does not support UPnP, you may consider upgrading your router.
If you have some technical skills and are comfortable with playing around your router settings, you may attempt to set up port forwarding manually. For more information on that see this article:
If your router is behind a Carrier Grade NAT (CGNAT), you need to call your ISP and ask for a public IP (rather than a shared IP address). If your ISP cannot offer that, you may consider switching to another ISP. For more information on this, take a look at the following article: