[gprimr1]

I need some help with UPNP and Folders with Kodi, which is running on an Android TV box, but I"m not sure if the issue is with UPNP or Android. 

I got a new computer for my birthday and I've been trying to get it up as my media server. It's nothing but problems.

I set up a Plex server and connected Kodi to it. That works for about 2 days, then it says "Cannot find network address" even though the server is running so I have to go back and add a new UPNP item. 

I tried the windows UPNP option, and that does the same thing, it works for a day or two, then stops. 

So I tried to do Windows Network Share. This worked great with my Seagate Goflex, but it's too small now. It says "invalid argument" when I try to browse the "workgroup" that the computer is connected to. I have network discovery on, and I can see the folders on my laptop. 

It's now to the point I can't play my media on Kodi devices.

[Klojum]

You seem to have problems with both different network types.

UPnP => probably different UPnP implementations on the various connected devices, which doesn't help. Any network issues, broken cables, faulty plugs?
SMB => SMBv1 on your initial Seagate Goflex, which will likely not support any higher SMB versions. Kodi prefers SMBv2 or higher, which also no longer supports network browsing. Hence your workgroup problem.
PLEX => Not my cup of tea. I have no experience with that system.

The solution AFAICT: make yourself a decent SMBv2+ (and MySQL?) server from an old PC (or NFS for that matter, using Ubuntu), so you can set up all Kodi devices as SMBv2 or higher.

[DarrenHill]

For the plex one - have you set the device that the server is running on to have a static IP address on your network?

If it's a device on DHCP (assigned network address) and you're turning it off and on again, it may be getting a different address each time from your router (or whatever is acting as the DHCP server and assigning IP addresses on your network) hence it's no longer where Kodi expects it to be and it can't be found. Setting it up again will incorporate the new IP address, but if that then changes again on a reboot then you're back to square one...

[gprimr1]

I was able to fix the Plex issue by rebooting the Tivo. 

I took the advice above and disconnected the Goflex from the network. I am now able to add the share as a manual SMB share.  

Thank you. Let's see if it continues to hold. The computer has a DHCP reservation so it'll never change IPs.