Hi Digger and welcome to the forum
We've been seeing this particular problem quite a bit recently, and it's solution is that you must use
W10 HOMEGROUPS networking, as many people who setup computer sharing with earlier versions of Windows prior to Win7, for instance XP and Vista, are using manual folder/volume sharing without a Server (as Neemo referenced in his post), is totally dependent on your networking skills being at least Intermediate to Advanced level to accomplish on 3 or more computers in this manner. The more computers, the more difficult it is to keep everything running, as any change you make such as rebuilding one of your computers on the network due to a crashed hard drive or Motherboard is going to zero out all the folder/volume shares you made, and you have to rip out all those shares and put them all in again--
ON EACH AND EVERY PC ON THE LAN!! This can be very time consuming and frustrating, even for us experts, and each time one of your network PCs crashes or malfunctions, you have to do it over and over and over again from scratch!
Not a lot of fun. That's why most small companies hire at least a part time network administrator to manage a small LAN. Microsoft simplified all of this back in 2009 with the advent of Homegroups. If you do
NOT have a server-based domain network, this is the only way to go for most small networks with <10 PCs or a small home office network, again <10 PCs.
Take a look at this post I did a week or two ago, where the User has very similar problems accessing his remote computers on his LAN. He applied the fix I linked to-and he's been up and running ever since; thanks to Microsoft Homegroups. Here's that link for you:
Network PC Needs Password
That should fix it for you!
Best of luck,
<<<BIGBEARJEDI>>>