Something strange happened here this week. we came back to work on Tueasday only to find that all my computers (mostly Macs) had changed subnet (Power outage ???) . My DHCP server (an ASUS Wireless Router RT-AC66U) normally attibute LAN IP addresses in the 192.168.1.xxx range. But on Tuesday, all my DHCP clients were on the 169.254.xxx.xxx subnet. Since my servers have fixed IPs (in my normal range) none of my clients were able to "talk" to my servers becausethey were essentially on two different subnets.
After hours of searching I finally came to the conclusion that my SWITCH was the culprit. Rebooting it did not solve the problem... That is to say, not right away. As it turns out, I can in the next day and everuthing appeared to be working fine...
All except for two computers that fome some reason can no longer connect to my file server (a QNAP TS-453Be). The sahre point originally appear in the Finder but disappear shortly after unsuccessful connexion.
I have tested the wiring between said computers and the switch and it would appear the problem lies either on the Swotch side or the computers themselves.
Do any of you care to suggest a solution to this problem or maybe a way to troubleshoot my way out of it?
Re: Troubleshooting avenues
It doesn't sound like a switch issue. The 169.254.0.0/16 subnet is known as link-local, it's what devices assign themselves when they can't acquire a DHCP address or have a static IP, and is set up so that computers can communicate directly to each other in the absence of any network management (these are not routable addresses, though).
It sounds more likely that something is wrong with the DHCP settings on the router itself than the switch, since your static IP devices do still work fine so the switch is passing traffic.