Why does the PC not see all computers on the local network if the settings are the same everywhere?

Question

Computer networks

Internet - Router (OpenWRT) - LAN.
DHCP, DNS - Openwrt.
Raised the Domain Controller on Server 2019. Mastered the dnsmasq configuration.
Added several PCs to the domain.
And then this problem surfaced: some PCs are not displayed in Explorer (Network item).
No settings have changed, everything was done in one day. Only DC, PC1, PC4
are visible A PC2, PC3 and PC5 are not visible.
At the same time, there is a ping, it also comes by name.
But why only for some?
Tried to update group policy via gpupdate - did not help.

Answer 1

Offhand, it is possible that the "Computer Browser" service is running on some PCs, it must be disabled and left on one (for example, on a DC). Also, offhand, firewall settings on a PC, for example: Network discovery, file and printer sharing.

Answer 2

It is possible more in detail about DNSMasq? You don't have AD, you raised only DNS and DHCP? Or what do you mean by dnsmasq on win?