Hello, I have an incredibly bizarre issue that is really puzzling my brains, this one is a real tough one so calling all network experts please. First I will give a short bit of background about the issue: On a completely random occurrence usually lasting 1-3 hours, the latency between any client and our router is very slow, this affects internet services and wireless networking, and the routers management page is incredibly slow to access. I have had discussions with the vendor and tried various things including updating firmware and resetting to factory settings to no success. The network setup: There are nearly a dozen devices on the network assigned a static IP address, these include the router, network printers, and servers. The routers IP address is 192.168.1.1. We use SBS 2008 as DHCP server and the range is 192.168.1.1 to 192.168.1.254 with an exclusion range of 192.168.1.1 to 192.168.1.10. The full DHCP configuration is detailed here (would be great if someone could just check these settings are ok as well): Item Details Scope Name My-domain.local Scope Range 192.168.1.1 to 192.168.1.254 Exclusion Range* 192.168.1.1 to 192.168.1.10 General Tab - Lease Duration* 8 Hours DNS Tab – Enable DNS Dynamic updates according to the settings below* Dynamically update DNS A and PTR records only if requested by the DHCP clients DNS Tab – Discard A and PTR records when lease is deleted* Enabled Scope Options – 003 Router 192.168.1.1 Scope Options – 004 Time Server* 192.168.1.7 Scope Options – 006 DNS Servers* 192.168.1.7, 192.168.1.1 Scope Options – 015 DNS Domain Name My-domain.local *indicates settings which have been changed from the default · IPv4 properties\advanced tab – conflict detection set to 1 All machines are domain joined machines, and no personal laptops were connected while experiencing this intermittent issue. The diagnostics: As stated earlier I have spoken to the vendor to troubleshoot the router side of things. I have also done the following extra steps: · Ran a continuous ping from my laptop to the router, the pings are slow averaging above 16ms and spiking to beyond 40ms sometimes · While the ping is running I have unplugged each network cable from the patch panel in turn to see if it was an IP address conflict, when I got to number 20 the pings sped up to 1ms, plug it back in and the pings slow down. So I thought I solved the problem… but… having found the machine this cable relates to, it’s a desktop running Windows 7, is domain joined and was in sleep mode at the time · I wake it up, check the pings – they go quick again, I put it back to sleep and the pings remain quick. I am assuming that when the machine woke up it refreshed its network IP address, and possibly received a new one. So, it could have been an address conflict right? IF this was the case, I have a few questions and pointers: · How/why does the machine get assigned the 192.168.1.1 address when this is in the exclusion range? (note: I haven’t been able to confirm that it did receive the address, if there is any way I can find this through client logs then that’s great, but the dhcp server logs don’t show it was ever assigned 192.168.1.1 · the machine in question used 192.168.1.18 until it went to sleep, when I woke it later it simply renewed its IP with the same address · when a machine goes into sleep is something happening to the network adapter to use 192.168.1.1? I don’t know the in depth technicalities of sleep mode and networking Finally, I have not been able to diagnose further, my next steps are to try and find out if this was simply a coincidence when I unplugged the network cable for this machine, or whether any machine on the network randomly experiences this problem. When this issue occurs again I will connect directly to the network port of the machine without waking it, and ping 192.168.1.1 to see if it’s alive, if it is then I’m guessing that confirms that somehow it gets assigned 192.168.1.1 if it doesn’t – then maybe it was just a coincidence and I am back to square one. We also receive BAD_ADDRESS quite a lot, all our machines are configured to go to sleep and people do use the sleep functionality. Is there any way to get rid of the BAD_ADDRESS errors, I thought DHCP clients remember their last IP address and try to obtain the same one? This is a small business network and the range is quite large in comparison to the 40 devices on it (some of which are static anyway). If anyone has any further advice or help I would greatly appreciate it. Many thanks, Steve