This does sound like some sort of network configuration problem and we are going to be limited in how much we can help you on this forum. We are OH experts, not networking experts.
If you can’t ping it and can’t ssh to it then the problem is going to be in your router/gateway, firewall, or on the RPi’s configuration.
So what is different about the one PC that can reach the RPi and your other machines? Are they using different subnet masks? Are any of them configured with static IP or are they all using DHCP?
These are not questions I want you to post the answers to here because I’m not going to be able to help even with the answers. But these are the sorts of questions you need to be asking yourself and based on what you find out searching google or perhaps posting to an RPi forum to figure out what the problem is.
It is very odd fore sure.