@pkks297 

try upgrading to the latest firmware.

https://static.tp-link.com/upload/firmware/2025/202505/20250528/ER605(UN)_V2.0_2.3.0%20Build%2020250428.zip

then enable ARP Detection on LAN interface

MR.S wrote

  @pkks297 

 

try upgrading to the latest firmware.

 

https://static.tp-link.com/upload/firmware/2025/202505/20250528/ER605(UN)_V2.0_2.3.0%20Build%2020250428.zip

Done

 

then enable ARP Detection on LAN interface

Please, can you help me how to do this? 

  @n0sh1t 

Yes, I'm using it as a standalone. I found the option "Enable ARP Spoofing Defense" under the "Firewall" section. Option was enabled and disabling it did not make any changes. I read instructions from this link configuring_firewall. I set up the firewall according to the instructions, and did bind IPs with MACs but did not make any changes. Still can't see all clients on DHCP client list. 

After that, I turned on the other switch. Clients connected to the first switch cannot see or ping clients on second and vice versa. All clients have internet access. Googling that problem I find out that there are two possible reasons for this phenomenon. Using Virtual LAN or bad routing. Since I'm not using VLAN and all the options related to it are turned off it looks like my router is having a lot of trouble doing the routing. 

  @pkks297 

pkks297 wrote

  @n0sh1t 

 

Yes, I'm using it as a standalone. I found the option "Enable ARP Spoofing Defense" under the "Firewall" section. Option was enabled and disabling it did not make any changes. I read instructions from this link configuring_firewall. I set up the firewall according to the instructions, and did bind IPs with MACs but did not make any changes. Still can't see all clients on DHCP client list. 

After that, I turned on the other switch. Clients connected to the first switch cannot see or ping clients on second and vice versa. All clients have internet access. Googling that problem I find out that there are two possible reasons for this phenomenon. Using Virtual LAN or bad routing. Since I'm not using VLAN and all the options related to it are turned off it looks like my router is having a lot of trouble doing the routing. 

 

 

That statement does not stand. If you have not touched the VLAN or routing table, they should be listed. If you use a different brand switch, we do not guarantee that the ARP discovery will work across the brands. At least with an Omada setup, all Omada gears, the DHCP, or the topology in the controller would properly display.  

And ARP sproof does not have anything to do with the function we discussed. You should take a peek at the VLAN1 interface. 

And there are many other misconceptions or misunderstandings of the product. 

You should also read the ARP table to learn if all devices are listed. Not reading the list from the DHCP list. 

Literally, DHCP list only lists whatsoever devices that send a DHCP request to the rotuer and it assigns a DHCP IP. If a device uses a static IP, it does not list. 

You should use the IP Statistics feature to scan your subnet to learn the list. That would be the proper way to learn the current devices in your network. That would be more informational than the DHCP list, which lists the subnet. 

Routing is a matter of layer 3. ARP is layer 2. They do not see or ping other clients on the switch, which does not mean anything for the router. The switch is layer 2 and if that does not work, it could be a problem with your switch. Meaning that ARP may not work. 

Unless you test the devices on the router directly, and they don't show up, they don't ping successfully, and they cannot access the Internet. 

The ping and other stuff may not even go to the gateway. I don't know if you have any config to the switches but this does not appear to be a problem with the router either way. 

  @pkks297 

pkks297 wrote

  @Clive_A 

I contacted TP-Link support and quickly got a solution. On the SG1016D switch, "port isolation" was turned on. After turning it off and rebooting, everything started to work fine. Thank you very much for your time and patience!

If you have any questions about the features of the switch/router, it is best to read the User Guide and learn what it does and how it works. That feature blocks the inter-port and layer 2 connections; therefore, it does not work for the list. 

Community members did not know this was enabled, so we cannot provide feasible suggestions. 

Anyway good to know it's resolved.