Can't connect with fixed IP, only DHCP works

[HotDoc]

Working on Win7 Pro x64 for years with same network settings - gigabit wired IPv4, fixed IP, fixed DNS, etc. Lot of other comps, network printers, APs - everything works fine. Suddenly last week my machine (only one) refused to connect - sometimes with yellow exclamation triangle on network icon, sometimes w/o it. But even if it tells "connected to internet" it does not connect to anything, even gateway. Few times it was resolved by reconnecting network cable. Trying various solutions without success. Then I noticed, that changing IP settings to DHCP solves problem - connection is back. Reverting to old fixed IP "disables" connection. I didn't install any new hardware or soft, only periodical software updates. Restoring system from "working" image made nothing. Have no idea - what's going on? Any way to fix or check what is a cause?

 

[UsernameIssues]

As strange as it may sound, some Access Points (AP/router combo) will not allow devices with static IP addresses to connect* if the IP address of the device is outside of the DHCP range. They claim it is a security feature. The AP/router can tie the IP address to a MAC address - thus making it like a static IP assignment - but within the DHCP range. That IP won't be assigned to any other device.

*connect can mean different things. The computer is in the router's list of connected devices, but the computer is not allowed to connect to the internet or any local network assets.


I mention the above info so that I can ask if the firmware in the network device handling DHCP might have automatically updated and started enforcing that type of "security". Or, perhaps the DHCP range got changed and this one computer is now outside of the DHCP range.

Also, what happens if you assign the problematic computer a different static IP address?

 

[HotDoc]

As strange as it may sound, some Access Points (AP/router combo) will not allow devices with static IP addresses to connect* if the IP address of the device is outside of the DHCP range. They claim it is a security feature. The AP/router can tie the IP address to a MAC address - thus making it like a static IP assignment - but within the DHCP range. That IP won't be assigned to any other device.

*connect can mean different things. The computer is in the router's list of connected devices, but the computer is not allowed to connect to the internet or any local network assets.

Thats not the issue - there's no new device in network and everything worked fine in curent enviroment. Some other devices are on fixed IP too and no problem with it.

I mention the above info so that I can ask if the firmware in the network device handling DHCP might have automatically updated and started enforcing that type of "security". Or, perhaps the DHCP range got changed and this one computer is now outside of the DHCP range.

DHCP server device is old enough to not receive any software updates. Nothing was changed in network settings.

Also, what happens if you assign the problematic computer a different static IP address?

Nothing happens, unfortunately. So I'm sure it's problem with this one particulary system, but I can't find source.
Assigning "problematic" IP to other device didn't casue any problem with communication.

 

[UsernameIssues]

Have you tried...

netsh winsock reset

and

netsh int ipv4 reset

...from an elevated command prompt?

 

[GokAy]

I was thinking an IP address conflict too, so will ask to try a different static IP as well.

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