Thank you for replying BobhWasatch
. Im pretty much a noob when it comes to this networking :/. The only thing i want is to portforward the listed ports to my specifik VM...
The port forwarding discussions on this forum are typically a setup where the Proxmox host is co-located at a data center and only has one public IP for multiple VM's. So it has to do the job a gateway router would normally do. In that scenario if you want to make services available to the Internet you have to do NAT and port forwarding on the Proxmox host. Most home or small office setups won't need to mess with that.
The "vmrbr0" device is a bridge. It is as if your VM's and the Proxmox host and the LAN the host sits on were all plugged into a physical switch you got from Amazon. Only difference is that it is "virtual", done in software. Then you give each VM an IP on the network and they can all talk to each other and also other devices on the network.
For instance, in my home network I have a Proxmox host at 192.168.1.9. The VM's are 192.168.1.10-20. My gateway router is 192.168.1.1. It has a switch with a bunch of ports, one of which has the Proxmox host plugged in along with other stuff like a networked printer.
If I hook up my Chromebook to the wifi, it gets a temporary address of let's say 192.168.1.135. I can then access the VM's on my Proxmox server from the Chromebook as if they were regular devices on the network. My DLNA (media) server VM can stream to my Chromebook, or I can use remote desktop to access the Windows 10 VM, and so forth. Likewise, the Windows VM can print to the network printer.
It all works exactly as if I had a bunch of physical PC's connected together. This is the out-of-the-box configuration. No extra setup is required. However, none of these can be reached directly from the Internet because the gateway router blocks that. Which is normally a good thing.
So if your intent is for other devices on the 192.168.87.x network to be able to connect to ports on the VM's running in Proxmox, you don't need port forwarding at all. Just access the IP of the VM and the port directly. Note that in the case of Windows VM's and some Linux distributions a firewall is set up by default
in the VM. Just like on a physical PC. You may need to configure that to allow external access.
If your intent is to allow people on the Internet to be able to access those ports, then you need to do the port forwarding on your gateway router, not on Proxmox (and you may still need to fiddle with the firewall in the VM).
Hope this helps.