Hi,
Since you and your husband each use separate Microsoft accounts and sign in with PINs, the reason you can see each other’s computers but can’t open them is because Windows won’t accept a PIN over the network it wants the actual Microsoft account email and password tied to that PC. To fix this, you can either sign in using that email/password combination (and if you don’t remember it, reset it at account.microsoft.com), or, if you’d rather not bother with passwords between your two home PCs, go into Control Panel > Network and Sharing Center > Advanced sharing settings and turn off "password protected sharing," which lets you connect without sign-in prompts. This comes down to whether you want the extra layer of security or the convenience of open sharing on your home network.
Kind regards,