I was attempting to connect 3 PC’s (Personal and two servers) via the TL-SG105 un-managed network switch. Beforehand i just connected one server and the personal pc into another switch i have. But i got this switch to accommodate this new server. However it seems as soon as i plugged in and turned on the new switch all of a sudden both servers no longer are able to recognize their cables. Personal PC is running linux mint, one server(the one i had before) is also running linux mint, and another server is running ubuntu 22.04.
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Home network consists of 1 comcast gateway (modem+router combo) with two ethernet LAN ports. One ethernet LAN port is connected to a seperate switch that functions perfectly for all other devices connected to it, the other is connected to TL-SG105.
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Personal PC can connect to internet just fine, either threw TL-SG105, or the other switch- I have attempted to plug both servers directly into the other switch and still no link.- Both servers show via ifconfig command that their respective ethernet flags indicate UP, but not RUNNING. Usually this means cable is not recognized. confirmed via ethtool command that link status is ‘NO’
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Swapped cables between all 3 devices on TL-SG105 and confirmed all cables are operational.
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Reset TL-SG105 multiple times during each swap of cable. And restart network manager multiple times as well as turned both servers on and off again.
Edit: I actually had to double check the switch, turns out i do have the SG105 not the SG105E. SG105E is managed, i have unmanaged.
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Its data sheet says it’s managed. It looks unmanaged, but I had a managed switch that was pre-set to use one port as uplink, and if you tried to do anything different, badness. I’m guessing there’s a way to set it up that’ll get you running.
I actually had to double check the switch, turns out i do have the SG105 not the SG105E. SG105E is managed, i have unmanaged. edit the post accordingly
If it’s a 5 port TP link switch, it’s important to start it up connected to the upstream router on the first port.
If it does not receive DHCP info (being assigned an IP by your router) when starting up, it will perform DHCP itself, which will cause chaos if your main router is trying to do the same.
That would explain this chaos. But how do resolve it? Resetting the router, then both switches does not seem to improve things.
Hmm the TL-SG105E is definitely a managed switch according to TP-Links website, maybe it has existing config on it?
Yes TL-SG105E is unmanaged. I went back and checked i just have TL-SG105
Start with layer 1. Are link lights on the NICs and switch ports on? Moving cables around, is there an issue with some ports and not others?
Yep All lights on the nics and switch ports are on. And as i mentioned in the post i swapped all the cables and double checked each of the ports. The cables seem to work just fine on the personal PC and swapped between all of the ports. Still unable to talk to the servers.
Not sure if this was resolved or not, but did you check for static IPs on devices? I ran into an issue when setting up the SG108E where even though I had Linux set to DHCP, it was assigning the manual entry. Rookie mistake 😞. Once I cleared the manual entries and cleared the static IPs from DHCP leases it cleared.
Hey, thanks for posting. The issue is not actually solved and it angers me so. I figured it might have something to do with the static ip, but I have Comcast so it literally takes a day for it to stop applying a static ip to a device. I will attempt to do this.
I would start with the minimal setup. Connect one of the non working machines to just the the switch, just to rule out any other equipment. Test all ports with this PC. repeat with the other two. Where are the similarities? Is something different?
Also, the TL-SG105E is a managed switch. Connect it to the working PC and open the web interface. Default IP of the switch is 192.168.0.1 if there is no DHCP lease. Make sure the IP is not used twice in your setup. Make a fimrware update, make a factory reset on the switch.
I actually had to double check the switch, turns out i do have the SG105 not the SG105E. SG105E is managed, i have unmanaged.
Alright, that makes it a bit easier. Any luck so far in debugging the problem?
I used to have one TL-SG105 and I solved this problem by connecting port 1 to the upstream router on first boot, so it can get an IP assigned by the router’s DHCP server and not create it’s own, breaking your entire network.
