Losing DHCP leased IP address after some time

Question

I'm running two NETGEAR switches in my network:

1 x NETGEAR JGS524PE (Latest firmware: 2.6.0.48, defaulting to 84.193.203.32)
1 x NETGEAR GS108Ev3 (Latest firmware: 2.06.14, defaulting to 192.168.0.239)

They are both configured to receive an IP address via DHCP, which they do initially or after I force them to refresh their IP address. But after some time, they lose their DHCP assigned IP address and revert to the (I assume factory default one) that I listed. These are IP addresses which lie outside the network subnet I am using, so if I want to access them I am unable to.

Both switches are having the same issue. All my other network devices (which are configured the same way and also get their IP address assigned over DHCP) do not exhibit this behavior, only the NETGEAR switches.

schumaku · Answer

Two issues in your post:&nbsp;Appears the Smart Managed Plus switch models are ignoring&nbsp;the common DHCP standards like a refresh at 50% and renewal on the time given by the DHCP server. Instead, they seem to have a hard coded renewal time of two hours. If the DHCP server isn't available, the devices fall-back to the default IP address 192.168.0.239.&nbsp;&nbsp;For the "effect" on the JGS524PE ... this is a DHCP assigned IP address. Suspect you have this switch exposed to the wild Internet, and your ISP does DHCP assign a telenet.be public IP address. Almost all Smart Managed Plus tiny management cores (except some XSxxxE variants) can't be limited to a designated management VLAN - so it can happen in such a set-up that the exposed switch will get the public IP address assigned. What can be very bad when your ISP does allow only one public IP address - intended&nbsp;for the router...

nickon · Answer

schumaku&nbsp;wrote:Appears the Smart Managed Plus switch models are ignoring&nbsp;the common DHCP standards like a refresh at 50% and renewal on the time given by the DHCP server. Instead, they seem to have a hard coded renewal time of two hours. If the DHCP server isn't available, the devices fall-back to the default IP address 192.168.0.239.&nbsp;That's useful knowledge. I don't know however why (the DHCP service on) my router wouldn't be available though? It's running 24/7, just like my switches.&nbsp;The only scenario that I can come up with where my router is down and my switches aren't is in case of a power failure and my switches are booting faster than my router. I've just recently renewed the IP addresses on both switches, so I'll try and check on a regular basis (daily) their DHCP assigned IP address and see if they lose it even if there weren't any device reboots / power failures.&nbsp;Thanks for chiming in.

schumaku · Answer

For the one exposed to the Internet (might be a bad idea in this switch class) I strongly suggest to put up a static IP address, for the ones on the LAN side only, it's just a suggestion.

nickon · Answer

You actually make a really good point there about the JGS524PE&nbsp;switch. I didn't notice that the IP address was actually a DHCP assigned (public) IP address handed out by my ISP instead of the factory default one...&nbsp;What is strange though is that if my switch is in this "public IP address assigned" state and I force a refresh of it's IP address through the ProSafe configuration utility, it is not getting a public IP address assigned from Telenet, but rather a static lease (192.168.1.2) assigned by my Ubiquiti Edgerouter (which is what I intend). It is only after some time that both of the switches get assigned another IP address (either the factory default one -- GS108Ev3 -- or the DHCP assigned public IP address --JGS524PE--).&nbsp;I'll shortly explain how (and the reason why) my switch is connected directly to my incoming ISP connection. The box provided by my ISP that I use to whatch tv (Telenet Digicorder) needs to get an IP address assigned from my ISP, and therefor should not be behind my home router, otherwise you can't access any interactive content on the box. So in order to achieve that I have a seperate VLAN (id:2) set on my&nbsp;JGS524PE on ports 14, 15 and 16:&nbsp;Port 14: Ubiquiti EdgeRouter Lite eth0 (WAN)Port 15: Telenet DigicorderPort 16: Incoming ISP connectionAll other ports are in the default VLAN (id:1) and my Ubiquiti EdgeRouter Lite eth1 (LAN) connects on one of these ports.

spuch · Answer

nickon&nbsp;I can confirm the problem with the dhcp leases. I have already documented it in this thread some weeks before. In my case my dhcp server was down due to a necessarry reboot of the operating system. It is a pity that the switch ignores all lease times pushed by the DHCP server and immediately falls back to a default IP address. It should at least try for some time to renew the IP address like access points do...

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Losing DHCP leased IP address after some time

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