Assuming all computers attached to the router are unchanged, the most simple explanations I can think of:
Wifi is configured as "guest network":
this is occurs on wifi only (and hardwired LAN connections would still work)
you configured your new wifi as a "guest network".
In a "guest network" the hosts (computers) sharing the same wifi are prevented from seeing each other. The purpose of this is that you wouldn't want someone visiting to be able to access your other computers, but instead only access the internet. See if your Wifi config is configured as guest network. Either disable "guest network" on that SSID, or set up a new SSID without "guest network" set.
Your new router has a new subnet:
Is your subnet is identical on your new router the same as your old? If you had 192.168.1.0/24 network defined before, you have that same network defined now (otherwise it could be software firewalls on your computers kicking in because they don't know this is your "home" network). Verify the subnet is the same as it was before. If not go to that other computer and disable file sharing, then re-enable it. Most consumer operating systems will prompt you to allow the software firewall on the computer to open the ports needed on that new IP.
DHCP reservations/IP assignments are now different:
Have you gone to your "192 type smb address thingie" and verified its still the same IP as before? If you weren't using static IP assignment or DHCP reservations, then the computer you're trying to connect to may have a new IP address because that information was defined before in your old router which isn't there now. Check the IP address on the computer you're trying to attach to.