Selfloop error on netgear switch

[orso7]

Dear tech community, I am reaching out for help.

I had some strange network errors at home for some time, found out ports on my switch (Netgear GS308T) just randomly "die". If I plug to another port, it works again, but the old one is dead (also if I connect something else). After some time (one or two days, sometimes longer) the next one dies to, and so on, a restart "revives" the ports. Looked up the logs and found a selfloop error, but even after researching and a reset+firmware update on the switch I can't by the love of god figure out where and how I created a selfloop and if that could be the thing that causes the ports to "die".

 

My network is quite simple, a Fritzbox as network/mesh master, and two Fritz mesh repeaters, the switch is connected to one of the repeaters to provide network in my home office/gaming room. As far as I can tell the only connection that "kills" the ports is the one between switch and repeater (cat6 cable, about 4m, I tried different ones, no change).

 

Any ideas? Should I deactivate STP (even if that should theoretically prevent loops, if I understand correctly)? The next idea would be buying a new switch.

 

These are the logs from today, one of the ports wasn't working and I changed ports a few times:

Spoiler

<179>1 2025-04-05T14:21:44.641+01:01 192.168.1.5-1 STP-3-SELFLOOP proto_stp.c(688) %% Dropping BPDU on Port GigabitEthernet2. Received BPDU SMAC (C8:9E:43:83:B9:99) same as that of interface
<182>1 2025-04-05T14:21:06.631+01:01 192.168.1.5-1 STP-6-PORT_STATE proto_stp.c(820) %% Port GigabitEthernet6 moving from Blocking to Forwarding
<182>1 2025-04-05T14:21:03.901+01:01 192.168.1.5-1 LLDP-6-NEIGHBOR_DISCOVER proto_lldp.c(4578) %% New neighbor on port GigabitEthernet6: Chassis ID D8:5E:D3:8A:24:C5, Port ID D8:5E:D3:8A:24:C5
<182>1 2025-04-05T14:21:03.881+01:01 192.168.1.5-1 STP-6-PORT_STATE proto_stp.c(820) %% Port GigabitEthernet6 moving from Disabled to Blocking
<181>1 2025-04-05T14:21:03.771+01:01 192.168.1.5-1 TRAPMGR-5-PORT_LINK_UP ksi_snmp.c(232) %% Interface GigabitEthernet6 link up
<182>1 2025-04-05T14:20:59.511+01:01 192.168.1.5-1 LLDP-6-NEIGHBOR_DEL proto_lldp.c(4320) %% Neighbor deleted on port GigabitEthernet6: Chassis ID D8:5E:D3:8A:24:C5, Port ID D8:5E:D3:8A:24:C5
<182>1 2025-04-05T14:20:58.131+01:01 192.168.1.5-1 STP-6-PORT_STATE proto_stp.c(820) %% Port GigabitEthernet6 moving from Forwarding to Disabled
<181>1 2025-04-05T14:20:58.941+01:01 192.168.1.5-1 TRAPMGR-5-PORT_LINK_DOWN ksi_snmp.c(230) %% Interface GigabitEthernet6 link down
<182>1 2025-04-05T14:19:33.621+01:01 192.168.1.5-1 STP-6-PORT_STATE proto_stp.c(820) %% Port GigabitEthernet2 moving from Blocking to Forwarding
<182>1 2025-04-05T14:19:31.031+01:01 192.168.1.5-1 LLDP-6-NEIGHBOR_DISCOVER proto_lldp.c(4578) %% New neighbor on port GigabitEthernet2: Chassis ID C2:39:6F:65:85:C2, Port ID C2:39:6F:65:85:C2
<182>1 2025-04-05T14:19:31.371+01:01 192.168.1.5-1 STP-6-PORT_STATE proto_stp.c(820) %% Port GigabitEthernet2 moving from Disabled to Blocking
<181>1 2025-04-05T14:19:31.351+01:01 192.168.1.5-1 TRAPMGR-5-PORT_LINK_UP ksi_snmp.c(232) %% Interface GigabitEthernet2 link up
<182>1 2025-04-05T14:18:54.511+01:01 192.168.1.5-1 LLDP-6-NEIGHBOR_DEL proto_lldp.c(4320) %% Neighbor deleted on port GigabitEthernet2: Chassis ID C2:39:6F:65:85:C2, Port ID C2:39:6F:65:85:C2
<182>1 2025-04-05T14:18:53.621+01:01 192.168.1.5-1 STP-6-PORT_STATE proto_stp.c(820) %% Port GigabitEthernet2 moving from Forwarding to Disabled
<181>1 2025-04-05T14:18:53.591+01:01 192.168.1.5-1 TRAPMGR-5-PORT_LINK_DOWN ksi_snmp.c(230) %% Interface GigabitEthernet2 link down
<179>1 2025-04-05T14:18:48.631+01:01 192.168.1.5-1 STP-3-SELFLOOP proto_stp.c(688) %% Dropping BPDU on Port GigabitEthernet2. Received BPDU SMAC (C8:9E:43:83:B9:99) same as that of interface
<181>1 2025-04-05T14:17:57.991+01:01 192.168.1.5-1 AAA-5-CONNECT login.c(158) %% New http connection for user admin, source 192.168.1.30 ACCEPTED
<179>1 2025-04-05T14:17:55.671+01:01 192.168.1.5-1 STP-3-SELFLOOP proto_stp.c(688) %% Dropping BPDU on Port GigabitEthernet2. Received BPDU SMAC (C8:9E:43:83:B9:99) same as that of interface
<180>1 2025-04-05T14:17:47.741+01:01 192.168.1.5-1 AAA-4-USER_REJECT login.c(251) %% New http connection for user admin, source 192.168.1.30 REJECTED
<181>1 2025-04-05T14:17:47.741+01:01 192.168.1.5-1 TRAPMGR-5-AUTH_FAIL login.c(245) %% Failed User Login with User ID: admin
<182>1 2025-04-05T14:13:08.611+01:01 192.168.0.239-1 STP-6-PORT_STATE proto_stp.c(820) %% Port GigabitEthernet2 moving from Blocking to Forwarding
<182>1 2025-04-05T14:13:05.011+01:01 192.168.0.239-1 LLDP-6-NEIGHBOR_DISCOVER proto_lldp.c(4578) %% New neighbor on port GigabitEthernet2: Chassis ID C2:39:6F:65:85:C2, Port ID C2:39:6F:65:85:C2
<182>1 2025-04-05T14:13:05.861+01:01 192.168.0.239-1 STP-6-PORT_STATE proto_stp.c(820) %% Port GigabitEthernet2 moving from Disabled to Blocking
<181>1 2025-04-05T14:13:05.611+01:01 192.168.0.239-1 TRAPMGR-5-PORT_LINK_UP ksi_snmp.c(232) %% Interface GigabitEthernet2 link up
<182>1 2025-04-05T14:13:05.611+01:01 192.168.0.239-1 STP-6-PORT_STATE proto_stp.c(820) %% Port GigabitEthernet6 moving from Blocking to Forwarding
<182>1 2025-04-05T14:13:03.621+01:01 192.168.0.239-1 LLDP-6-NEIGHBOR_DISCOVER proto_lldp.c(4578) %% New neighbor on port GigabitEthernet6: Chassis ID D8:5E:D3:8A:24:C5, Port ID D8:5E:D3:8A:24:C5
<182>1 2025-04-05T14:13:03.611+01:01 192.168.0.239-1 STP-6-PORT_STATE proto_stp.c(820) %% Port GigabitEthernet6 moving from Disabled to Blocking
<181>1 2025-04-05T14:13:03.391+01:01 0.0.0.0-1 TRAPMGR-5-PORT_LINK_UP rsd_l3_intf.c(130) %% Interface VLAN-MGMT link up
<181>1 2025-04-05T14:13:03.381+01:01 0.0.0.0-1 TRAPMGR-5-PORT_LINK_UP ksi_snmp.c(232) %% Interface GigabitEthernet6 link up
<182>1 2025-04-05T14:12:58.511+01:01 0.0.0.0-1 LLDP-6-NEIGHBOR_DEL proto_lldp.c(4320) %% Neighbor deleted on port GigabitEthernet6: Chassis ID D8:5E:D3:8A:24:C5, Port ID D8:5E:D3:8A:24:C5
<182>1 2025-04-05T14:12:57.611+01:01 192.168.0.239-1 STP-6-PORT_STATE proto_stp.c(820) %% Port GigabitEthernet6 moving from Forwarding to Disabled
<181>1 2025-04-05T14:12:57.591+01:01 192.168.0.239-1 TRAPMGR-5-PORT_LINK_DOWN ksi_snmp.c(230) %% Interface GigabitEthernet6 link down
<181>1 2025-04-05T14:12:57.591+01:01 192.168.0.239-1 TRAPMGR-5-PORT_LINK_DOWN rsd_l3_intf.c(118) %% Interface VLAN-MGMT link down
<182>1 2025-04-05T14:09:32.011+01:01 192.168.0.239-1 LLDP-6-NEIGHBOR_DISCOVER proto_lldp.c(4578) %% New neighbor on port GigabitEthernet6: Chassis ID D8:5E:D3:8A:24:C5, Port ID D8:5E:D3:8A:24:C5
<182>1 2025-04-05T14:09:22.601+01:01 192.168.0.239-1 STP-6-PORT_STATE proto_stp.c(820) %% Port GigabitEthernet6 moving from Blocking to Forwarding
<182>1 2025-04-05T14:09:20.351+01:01 0.0.0.0-1 STP-6-PORT_STATE proto_stp.c(820) %% Port GigabitEthernet6 moving from Disabled to Blocking
<181>1 2025-04-05T14:09:20.201+01:01 0.0.0.0-1 TRAPMGR-5-PORT_LINK_UP ksi_snmp.c(232) %% Interface GigabitEthernet6 link up
<181>1 2025-04-05T14:09:20.201+01:01 0.0.0.0-1 TRAPMGR-5-PORT_LINK_UP rsd_l3_intf.c(130) %% Interface VLAN-MGMT link up
<182>1 2025-04-05T14:09:18.101+01:01 0.0.0.0-1 STP-6-PORT_STATE proto_stp.c(820) %% Port GigabitEthernet6 moving from Forwarding to Disabled
<181>1 2025-04-05T14:09:17.881+01:01 192.168.1.5-1 TRAPMGR-5-PORT_LINK_DOWN rsd_l3_intf.c(118) %% Interface VLAN-MGMT link down
<181>1 2025-04-05T14:09:17.871+01:01 192.168.1.5-1 TRAPMGR-5-PORT_LINK_DOWN ksi_snmp.c(230) %% Interface GigabitEthernet6 link down

 

 

[Kilrah]

Make a diagram. You're sure your switch isn't connected to both the repeater and the master?

 

If there's a loop then STP is what's preventing your network from going down by disabling the port, otherwise you'd just max out everything.

[orso7]

2 hours ago, Kilrah said:

Make a diagram. You're sure your switch isn't connected to both the repeater and the master?

 

If there's a loop then STP is what's preventing your network from going down by disabling the port, otherwise you'd just max out everything.

I am quite sure, at least there is no additional cable running there, that would have to go through at least one wall.

EDIT: There are of course some more wifi devices on there like phones, my wife's laptop, TVs,  tablet and so on.

 

[ISharkI]

Hi,

 

that log you posted was from one of the Fritz devices or the Netgear one? It seems to be jumping between Port GigabitEthernet6 and GigabitEthernet2. Could you mark in your diagram where those ports are connected?

Also the log mentions a "VLAN-MGMT" that goes up and down. Do you use VLANs in your setup?

What does your second repeater do? Only extending wireless coverage or is anything connected there too?

 

[orso7]

11 hours ago, ISharkI said:

Hi,

 

that log you posted was from one of the Fritz devices or the Netgear one? It seems to be jumping between Port GigabitEthernet6 and GigabitEthernet2. Could you mark in your diagram where those ports are connected?

Also the log mentions a "VLAN-MGMT" that goes up and down. Do you use VLANs in your setup?

What does your second repeater do? Only extending wireless coverage or is anything connected there too?

 

The log is from the Netgear switch. The logs of the Fritzbox router are without any errors. 

 

The jumping thing was probably me changing ports on the switch. Some of those errors come up as soon as I plug a device into a "dead" port. As of right now, Ethernet 2 is connected to the repeater and Ethernet 6 is my main PC, Ethernet 7 is the 3D Printer but that's currently off. If I remember correctly Ethernet 5/4/3 are dead rn, haven't done a restart in the meantime.  

 

For config I left the switch almost completely "as is" after the reset/update. There is nothing configured other than the absolute basics (name, time, password). The IP is provided via the DHCP from the main router (reservation for a static IP). The second repeater is just for coverage in the kitchen, it is wifi only. 

 

EDIT: When I look into the switches port configuration page it also says under "administrator mode" that 3/4/5 are deactivated, no option to activate here.

[ISharkI]

Is it possible the repeater at the bottom is reaching the fritzbox at the top connection wise? One theory could be an STP packet bouncing around the wireless repeaters and getting delivered back to the netgear switch. But I have not used a Fritz repeater ever so I am not sure about this.

 

Another one could be a problem with the NAS not being attached to the netgear but to the Fritz repeater and sending back some stuff from time to time

[orso7]

23 hours ago, ISharkI said:

Is it possible the repeater at the bottom is reaching the fritzbox at the top connection wise? One theory could be an STP packet bouncing around the wireless repeaters and getting delivered back to the netgear switch. But I have not used a Fritz repeater ever so I am not sure about this.

 

Another one could be a problem with the NAS not being attached to the netgear but to the Fritz repeater and sending back some stuff from time to time

Yes, that is possible. But how can that be a problem, I thought the whole idea about mesh wifi is that it does all this on its own and the user does not have to watch out.

 

About the NAS, the Fritz Repeater has two ethernet ports, both are specified in the manual to be used as normal connection ports. The Synology NAS does only provide some file shares for data, no specials like plex server or something like that.

[ISharkI]

Your mesh wifi does what it is supposed to do. Connect everything together without user intervention.

 

Spanning Tree Protocol is a network protocol, like FTP, Samba etc. It tries to determine if somewhere is a loop in your network and prevents broadcast-storms and the like (which would totally suffocate your regular connections).

Quote

While the FRITZ!Box itself might use a mesh system with features that resemble aspects of STP, the FRITZ!Repeater doesn't need to implement STP in the same way as a traditional switch.

So if you are totally sure you do not and will never have loops in your network you can simply disable STP. Though I would not recommend this without knowing the cause. 

But if you want to try you can disable it as a test and see what happens. Worst case you get an "Internet outage" and need to restart all devices...

 

Another thread on the internet had a different setup but still Fritz and Netgear with repeaters. There he reached out and was told to disable "Energy Efficient Ethernet"... Not sure if that applies to your cause but might be worth a try.

Quote

Steps to Disable EEE on the FRITZ!Repeater:

1.Access the FRITZ!Repeater interface by entering its address in your browser.

2.Navigate to Hilfe und Info (Help and Info) in the left menu.

3.Click on FRITZ!Repeater Support at the bottom of the page.

4.In the Ethernet Compatibility section, enable the option Disable EEE (Energy Efficient Ethernet).

5.Save the changes by clicking Apply Settings.

 

[orso7]

On 4/8/2025 at 1:04 PM, ISharkI said:

Your mesh wifi does what it is supposed to do. Connect everything together without user intervention.

 

Spanning Tree Protocol is a network protocol, like FTP, Samba etc. It tries to determine if somewhere is a loop in your network and prevents broadcast-storms and the like (which would totally suffocate your regular connections).

So if you are totally sure you do not and will never have loops in your network you can simply disable STP. Though I would not recommend this without knowing the cause. 

But if you want to try you can disable it as a test and see what happens. Worst case you get an "Internet outage" and need to restart all devices...

 

Another thread on the internet had a different setup but still Fritz and Netgear with repeaters. There he reached out and was told to disable "Energy Efficient Ethernet"... Not sure if that applies to your cause but might be worth a try.

 

Sorry for the late response, I've been away for two weeks and couldn't try. Thank you for digging up this information, I will report back if it helped. 

[orso7]

Ok, I tried different settings and setups but the problem still occurs. Sometimes only once a week and sometimes two times a day.

 

Looks like I will need to drill some holes.