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--- troubleshooting:dhcp_server_problems [2010/11/29 10:32] – mats
+++ troubleshooting:dhcp_server_problems [2010/12/01 14:51] (current) – mats
@@ Line 1: / Line 1: @@
 ====== DHCP Server problems ======
-This deals with the DHCP Server in the Internet Gate, distributing IP addresses to clients on the LAN.
+This deals with the DHCP Server in the Internet Gate, distributing IP addresses to clients on the LAN.\\
+The DHCP Server is configured partly on the [[web_gui:network_page#DHCP Server|Network Configuration]] page, partly on the [[web_gui:dhcp_server|DHCP Server - Advanced]] page.
+Read more: [[wp>DHCP|DHCP]]
 ===== IP address collisions =====
@@ Line 80: / Line 83: @@
 The DHCP server has a stategy that when a new host (with a previously unknown MAC address) appears, it will get an IP address that is totally unused, that is, it is not present in the stored //lease database//.
 Only when the server is running short of addresses, because the whole pool is used, it starts using IP addresses that really was reserved for another, currently unseen (=not connected) host, thus deleting the old host from the database.
+===== Why can't my PC get an IP address? =====
+  * Is there an Ethernet link at all, both in the PC and with the Internet Gate? (See also [[connect_to_gui|here]])
+  * Does a static IP address work? To try that, set the IP interface of your PC to static instead of dynamic address (on Windows, this is done in the Control Panel, Network Connections). Choose an IP address that is within the same subnet as the Internet Gate's local interface (for example 192.168.0.5).
+  * If the static IP address works, but not the dynamic (by DHCP, "Obtain an IP address automatically") check the following:
+    * Is the address range too small in the Internet Gate? It could be increased on the [[web_gui:network_page#DHCP Server|Network page]].
+    * Could there be an IP collision case, as described [[dhcp_server_problems#IP address collisions|above]]? Some DHCP clients, when getting a new IP address, check if anybody on the LAN answers on this address (by an ARP request), and refuse to use this address if it is found already in use by another host. If this is suspected, do:
+      - Disconnect //all// hosts from the LAN
+      - Click the **Reset** button under **IP address lease status** on the [[web_gui:dhcp_server#IP address lease status|DHCP Server - Advanced]] page.
+      - Reconnect all hosts again one-by-one so that each host in turn will get its IP address refreshed from the Internet Gate.
+    * If it is suspected that the //lease database// in the Internet Gate has been lost, or is wrong (maybe the unit has been moved to a new network, or factory reset), do the same procedure as above.
+  * If the static IP address doesn't work either, check the cables and the IP address used (see also [[connect_to_gui|here]]). Only when this works, switch to a dynamic address in the PC.