Next step: You mention having multiple iMacs. Does this happen on all of them, or only on one of them?
Try "washing" your DSL modem <http://www.macsrwe.com/blog/?p=38>. I know it sounds like voodoo, but these DSL units are damn freaky. (I'm envisioning a bug where the modem may have a reserved address configured for the problem iMac, and/or may be disturbed to changes in the MAC address environment for it.) Try logging into your router with a browser. See if it keeps some sort of log, and what it has been saying about these connection attempts. Look at its list of attached devices, and check for any discrepancies (e.g., your iMac still showing up on its native jack even though it is gone). > On Apr 14, 2020, at 10:41 AM, Jeff Weinberger <[email protected]> wrote: > > On Tue, Apr 14, 2020 at 1:37 PM Macs R We <[email protected] > <mailto:[email protected]>> wrote: > Oh, yeah. > > The big question: have you tried connecting the Mac to a different port on > the switch? > > Good question and yes, I've tried all the open ports and even switched the > iMac with other devices so I was connecting it to ports I know work. > > When the IP address flashes up, does it start with the assigned range for > your router (usually 192.168…, or 10…, or 172.16…), or does it begin with > 169.254...? > It starts with 192.168...which is the assigned range by the router > > > What brand and model is your router? > > It's whatever cable modem/router/wifi combination that came from my Verizon > ISP service > > > > >> On Apr 14, 2020, at 10:27 AM, Jeff Weinberger <[email protected] >> <mailto:[email protected]>> wrote: >> >> On Tue, Apr 14, 2020 at 1:12 PM qb <[email protected] <mailto:[email protected]>> >> wrote: >> Just to make sure: when the MacBook WORKS - you have the WiFi OFF right? :-) >> >> Sorry - meant to specify - yes, the wifi is off. >> >> And you mentioned other devices on the wired network - meaning plugged into >> the SWITCH? >> >> The other wired devices on the network are all plugged into the switch. Only >> the iMacs and the switch are plugged into the router. There are wireless >> devices connected to the WiFi from the router. >> >> thx >> >> > On Apr 14, 2020, at 1:08 PM, Jeff Weinberger <[email protected] >> > <mailto:[email protected]>> wrote: >> > >> > Hi - any help here is much appreciated!! >> > >> > My iMac's (Retina 4K 21.5 inch Late 2015, OS/X 10.15.4) Ethernet will not >> > connect when it is connected to a switch (NetGear GS108 ProSafe 8 port >> > gigabit unmanaged switch) which is in turn connected to my router. It >> > connects fine when the iMac is connected to the router directly. Here's >> > what happens: >> > >> > When I connect the iMac to the router, it picks up and handles the DHCP >> > connection as you'd expect - it gets an IP address and works fine. When I >> > connect the iMac to the switch, the traffic indicator lights on the switch >> > flash as expected, then it looks (in the Network preference pane) as >> > though it got an IP address then loses it and tells me either "unable to >> > connect" or "cable disconnected." It repeats this quick >> > connect-then-disconnect about every 30 seconds and cannot maintain >> > connection. >> > >> > I have tried using different cables which I know work when connected to >> > other devices and to the switch, with the same outcome. If it matters, >> > this happens with both iMacs (my only desktops), but does not happen with >> > a MacBook Air (ethernet to USB-C) or any other devices on the wired >> > network. >> > >> > My network settings are set to DHCP and the hardware port to automatic. >> > >> > I am switching to a different network configuration that will require that >> > I connect all the devices (including the two iMacs) to the switch, so I >> > need to sort this one out. >> > >> > Any thoughts, ideas or suggestions are very much appreciated! >> > _______________________________________________ >> > MacOSX-talk mailing list >> > [email protected] <mailto:[email protected]> >> > https://www.omnigroup.com/mailman/listinfo/macosx-talk >> > <https://www.omnigroup.com/mailman/listinfo/macosx-talk> >> >> _______________________________________________ >> MacOSX-talk mailing list >> [email protected] <mailto:[email protected]> >> https://www.omnigroup.com/mailman/listinfo/macosx-talk >> <https://www.omnigroup.com/mailman/listinfo/macosx-talk> > > -- > Macs R We -- Personal Macintosh Service and Support > in the Wickenburg and far Northwest Valley Areas. > http://macsrwe.com <http://macsrwe.com/> -- Macs R We -- Personal Macintosh Service and Support in the Wickenburg and far Northwest Valley Areas. http://macsrwe.com
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