We are upgrading networking hardware in small network (< 20 computers). It uses Windows Home Server on an Acer box as the file server. Internet<--->DSL connection<-->ethernet<-->NetGear Wireless/wired router<--->Cisco switch The Cisco switch has 16 ports, and all of the wired machines are normally connected to it. We don't expect to use the wired ports on the NetGear box. Starting around Chritmastime, machines started losing wired and wireless Internet connectivity. One symptom seems to be related to new machine joining the network. Machine #2 connect using the wireless network, and machines #1 (previously connected) loses connectivity. The problem also existed with the older router, a LinkSys WRT54G unit that doesn't support 802.11n. I'd normally suspect a routing problem, and from one laptop I do see a "preferred route" for network 169.254.0.0. The NetGear router (a WNDR 3700) is configured with a static IP address and fixed DNS server settings, per arrangement with the ISP. These settings do provide internet connections, it's just that they are intermitted. The DSL line never seems to be losing connectivity, as the green light on the Willtel box stays on constantly. The NetGear router doesn't appear to have assigned the IP address associated with the 169.254 router (which is a "ZeroConf" address, normally associated with Apple's BonJour system.) I have three questions Q1) Why isn't there be a "preferred route" through the NetGear router (192.168.1.1)? There already seems to be a default route to 0.0.0.0 through the NetGear's IP address. with a metric of 10. There is persistent route advertised through 192.168.1.112 with a metric of 1 (see netstat output below). This strongly suggests either a misbehaving network device, or possibly a dual-homed machine elsewhere on the network spreading bogus routing, which isn't valid on this network. When this same laptop loses connectivity, the default route is hosed. I can no longer ping the router, even with a wired connection Ping 192.168.1.1: 192.168.1.2 Destination host unreachable (that's the address of the machine I'm sitting at!) Ping 127.0.0.1: (works as expected) Q2) Could any ethernet-level settings (like Jumbo Frame support) be affecting wireless connections as well as wired ones? XP machines are similarly dropping network connections, so the problem isn't limited to Windows 7 machines. Q3) What troubleshooting tools are best in these situations? I can use ping and traceroute, but when the local system's IP address in unreachable, they aren't very effective. I have access to Linux systems and can configure static IP address on the local 192.168 network Additional details (output of the netstat command): =========================================================================== Interface List 14...0c ee e6 9b 6c d1 ......Microsoft Virtual WiFi Miniport Adapter 12...0c ee e6 9b 6c d1 ......Dell Wireless 1397 WLAN Mini-Card 11...00 26 b9 08 68 2c ......Realtek PCIe GBE Family Controller 1...........................Software Loopback Interface 1 18...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #2 13...00 00 00 00 00 00 00 e0 Teredo Tunneling Pseudo-Interface 19...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #3 17...00 00 00 00 00 00 00 e0 Microsoft ISATAP Adapter #4 =========================================================================== IPv4 Route Table =========================================================================== Active Routes: Network Destination Netmask Gateway Interface Metric 0.0.0.0 0.0.0.0 192.168.1.1 192.168.1.2 10 127.0.0.0 255.0.0.0 On-link 127.0.0.1 306 127.0.0.1 255.255.255.255 On-link 127.0.0.1 306 127.255.255.255 255.255.255.255 On-link 127.0.0.1 306 169.254.0.0 255.255.0.0 192.168.1.112 192.168.1.2 11 192.168.1.0 255.255.255.0 On-link 192.168.1.2 266 192.168.1.2 255.255.255.255 On-link 192.168.1.2 266 192.168.1.255 255.255.255.255 On-link 192.168.1.2 266 224.0.0.0 240.0.0.0 On-link 127.0.0.1 306 224.0.0.0 240.0.0.0 On-link 192.168.1.2 266 255.255.255.255 255.255.255.255 On-link 127.0.0.1 306 255.255.255.255 255.255.255.255 On-link 192.168.1.2 266 =========================================================================== Persistent Routes: Network Address Netmask Gateway Address Metric 169.254.0.0 255.255.0.0 192.168.1.112 1 =========================================================================== IPv6 Route Table =========================================================================== Active Routes: If Metric Network Destination Gateway 13 58 ::/0 On-link 1 306 ::1/128 On-link 13 58 2001::/32 On-link 13 306 2001:0:4137:9e76:14ba:586:3f57:fefd/128 On-link 11 266 fe80::/64 On-link 13 306 fe80::/64 On-link 13 306 fe80::14ba:586:3f57:fefd/128 On-link 11 266 fe80::39d5:6cca:d2f6:8f40/128 On-link 1 306 ff00::/8 On-link 13 306 ff00::/8 On-link 11 266 ff00::/8 On-link =========================================================================== Persistent Routes: None