Hello, Ivan.
Before we get into troubleshooting your configuration, let us note that hosting Internet-facing web applications by UltiDev Cassini
is risky.
As for the problem you have described, we think it is more likely that you are having a problem with TCP/IP routing, rather than with UltiDev Cassini. If you can go to the PC2 and access an application at PC1, then it is definitely a routing problem, because for Cassini server running on PC1 there is absolutely no difference whether the request is coming from 192.168.0.3 or 192.168.0.1. If you happen to have another web server on PC1, like IIS or Apache, try hosting a simple HTML page there and set up your router to point to that application and see whether that works.
Also, please check your software firewall on PC1 and whether it blocks inbound traffic on PC1. UltiDev Cassini installer punches a hole in the Windows Firewall for itself, but if you use a software firewall from another vendor, you may need to configure it manually.
Please let us know if this information has helped.
Best regards,
UltiDev Team.
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