One PC not visible to others on same network.

I have three PC's on my LAN homegroup, two laptops and one desktop that functions as a media server. The Desktop is also the one that created the home group. the laptops can join the homegroup and media streaming works between my Smart TV and the desktop, but neither laptop can see the desktop on the network or access shared folders.

I ran the Network Troubleshooter and proceeded through the wizard and received the message attached to this post. Something on my PC is performing Network Address Translation. Also, NAT is enabled on my router, and I want it to stay enabled. Unfortunately, nothing in the troubleshooter tells me where the other device is that's performing NAT on the PC nor how to disable it..

Any help would be appreciated.

Other things of note, All three PC's use a the ExpressVPN client with killswitch disabled. All three use Comodo firewall which is setup to function as the VPN disconnect killswitch. all three PC's use AVG antivirus. The problem persists even when the firewall, VPN client and antivirus software is disabled. Also worth noting, File sharing and network discovery are enabled on all PC's.

Double Nat(ting) can be an issue , usually happens when you hook one Router to Another......

Do you have a BB (Broadband) Modem/Router too ? as well as your Own Router , if yes see if the BB Router allows you to Bridge Port 1 and use that for your Router.

Also check that Netbios Over TCPIP is Enabled on all computers , Win10 disables it on some systems , and you end up with some computers seeing but not seen etc on the Lan. ( its on the Advanced Tab of the IPV4 and IPV6 Protocol , on the Wins Tab.)

It seems the problem originated in Comodo.  IPv6 Filtering was enabled. I remember setting that up specifically to avoid bit torrent clients from allowing IPv6 connections if the VPN went down, however after doing some testing, this doesn't appear to be happening with now even with IPv6 filtering disabled.

Try this...

A small registry hack is all it takes to get around the issue by creating a policy manually that overrides the default setting. Do this on the server that has the shares you want to access remotely:

1. Click the Windows Start icon and search for “regedit”. Right-click and select “run as administrator”.
   
2. Expand the tree to HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft\ Windows \ CurrentVersion \ policies \ system.
3. Create a new key (Right click -> New -> choose “DWORD Value (32bit)”).
4. Name the key “LocalAccountTokenFilterPolicy” and give it the value of “1”. Click OK.
5. Reboot the server to enable the setting to take effect.
6. Now when you try to access the administrative shares on the remote computer, it should magically work.

Reply if this works for you!