Or of a hardware appliance of the sort that do NAT and port forwarding? DHCP might even be utilizing ports 67 and 68 on some systems Is the DHCP service running on the clients? Something may be wrong with DNS? DNS server names are handed out with DHCP leases to clients. If it is misconfigured on the DHCP server it could of course cause problems.

Enable or Disable Windows Firewall from Command Prompt Nov 06, 2017 Blocking DHCP in Windows Firewall Sep 23, 2013

Jan 08, 2016

Ports used for connections - Configuration Manager By default, the HTTP port that's used for client-to-site system communication is port 80, and the default HTTPS port is 443. Ports for client-to-site system communication over HTTP or HTTPS can be changed during setup or in the site properties for your Configuration Manager site.

Configure an IPv4 DHCP Server - WatchGuard

-p portnum — Specifies the UDP port number on which dhcpd should listen. The default is port 67. The DHCP server transmits responses to the DHCP clients at a port number one greater than the UDP port specified. For example, if the default port 67 is used, the server listens on port 67 for requests and responds to the client on port 68. How to Configure the DHCP Service | Barracuda Campus Nov 10, 2017 Services — DHCP — Configuring DHCP Relay | pfSense Optionally check the box to Append circuit ID and agent ID to requests, and then enter an IP address for the Destination server which is the actual DHCP/DHCPv6 server. Note Relay may not work as intended from the firewall if the target DHCP server is across an IPsec tunnel. Kerberos and Firewalls | University IT Jan 08, 2016