Question Connection to NAS affected by power surge

May 18, 2019
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I have a wired network with two Western Digital PR4100 (NAS), and several Windows 10 workstation, plus one Windows 7. I have a Zyxel modem/router and TPLink switch. No wifi.

About a month ago I was hit with a power surge that knocked out power for about 10 seconds. No, I don't have a UPS protecting my two NASs. Ever since that power surge, my Window 7 Home PC is unable to connect to one of the two NAS with any regularity. Prior to the surge, everything worked perfectly. The other NAS connection is ok about 80% of the time but it will sometimes drop as well. The Windows 10 PCs connect with both NAS ok.

After the power surge:
I replaced both NAS under RMA, so the enclosures are brand new (thinking the network card within each might have been damaged).
I replaced the NIC in my Win7 PC.
I replaced the switch.
I replaced the modem/router.

After all that, I can still only connect to one of the two NAS with regularity.

If I unplug the LAN cable from the back of the NAS I'm having trouble with, and then plug it back in, I have access to that NAS from my Win7 machine for several minutes only to have it drop again. I've tried turning off my firewall and anti virus. Didn't help. I've turned off/on network file sharing which results in a brief moment of connectivity.

Interestingly, I can always PING from my Win7 to NAS, so I know the connection is alive at a very low level.

Anyone have any other ideas that I may have missed, short of replacing this Win7 pc (which I'll probably need to do early next year anyway).

Thanks in advance.
 

Ralston18

Titan
Moderator
Sketch out your network to include all devices.

Check the modem router - ensure that its' intended configuration is intact.

Then check each device for its' respective IP address and subnet mask. Record on the sketch.

My thought is that there may some IP address duplication occurring.

Check the router for the dynamic (DHCP) IP address range and that any static IP addresses (e.g., NAS boxes) are still being reserved as intended via the applicable NAS box MACs. And that those static IP addresses are outside of the allowed range of DHCP IP addresses established within the router.
 
May 18, 2019
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Thank you for your thoughts. As you had suggested, I think the problem stemmed from an IP address conflict.

When started the process of network mapping as you suggested, I found that my router was "holding" a static IP address that duplicated the IP address of the NAS in question. I changed the IP address of my NAS and like magic, everything worked (so far). I also reset my DHCP range to a value below any of my static devices just to avoid any more possible conflicts.

Still, I am really baffled as to why my router is holding on to this IP address. I powered off every single device, turned on the modem/router and a single PC so I could log on to the router. The router's map showed my PC, plus that single static IP address in question even though every other device was still powered off. I was even able to ping it. Not that it matters this much at this point, but I'm still bugged as to why my router is holding on to this IP address. Keep in mind that I just swapped the modem/router last week Thursday with a brand new unit so I would have thought that any legacy mapping would have been gone.

But thank you for pointing me in the right direction!!!
 

Ralston18

Titan
Moderator
Static IP addresses are established for devices whose IP address should not change and that static IP is reserved by using the device's MAC.

Unless that reservation is cleared from the router then the next time the device is found/discovered on the network (via its' MAC) the device is assigned the applicable reserved Static IP address.

As for "legacy mapping" the following links may provide some insight as to what occurred.

https://www.lifewire.com/beginners-guide-to-arp-4096766

https://www.techjunkie.com/clear-arp-cache/

The TPLink Switch.....