Some DHCP reservations are unstable or failing for specific IP addresses.
Some DHCP reservations are unstable or failing for specific IP addresses.
I'll start by saying that I'm using the cheapest router/ap that Walmart had when I needed one five years ago in college. It's a Linksys e5350 AC1000. I have a NAS, a desktop, and a laptop, and I want them to have static IPs since I'm setting up SSH, file shares, etc. I'm using DHCP reservations in the router to do this, since it seems like the more effective strategy to me (centrally managed, don't have to worry about switching my laptop back to DHCP when I take it out of the house.) When it works, it works. But it's not working sometimes. More than once now, a computer has not been able to get an address from the DHCP server (assigning itself to 169.etc). If I go into the DHCP reservations and change to a different IP address, that usually fixes it. I'm no networking expert so I'm wondering if there's something I'm missing here. The addresses I'm trying to reserve are at 20 and below so they're faster to key in when I need to. I know not to use 192.168.1.1 because that's the router's address. Are there other reserved addresses that I'm not aware of that I'm clashing with? The DHCP server is assigned to 100-199. Other potentially relevant info: The desktop and laptop are running Debian. I've been using `sudo dhclient -r` and then `sudo dhclient` to get the machines to release their DHCP lease and refresh it, which (when it's working) gets the computer to switch to whatever address is reserved for it in the DHCP server. Any ideas? Is there something I can do or is my router just a piece of junk?
Don't require a DHCP reservation if the IP isn't within your range. Configure the addresses directly on your devices. The router may not manage reserved addresses correctly when they fall outside its DHCP coverage.
I wouldn't suggest fixing IP addresses permanently on the device. I did this for years before noticing how much trouble it caused with more gadgets (though routers back then were simpler and many didn't support reservations). It's also normal for a router to require a specific reservation outside the DHCP range, in the same subnet. This makes it easier for the router to handle reserved versus dynamic IPs, preventing conflicts.
It might relate to dual-booting. The DHCP server may not accept changes to the hostname while keeping the MAC address fixed. The issue reoccurred after restarting the desktop, so the IP was previously set manually.
When properly set up, DHCP reservation operates inside the designated address range. This means a pool spanning 192.168.1.100 to 192.168.1.199 will allow a client receiving 192.168.1.110 to be assigned that IP and MAC address, preventing other devices from claiming it. Attempting to reserve an IP outside this range often causes the issues you're facing. Opting for manual static assignments is an alternative, though it becomes cumbersome if clients attempt to connect across networks. You cannot effectively use both methods simultaneously.
I understand your point. Could you provide examples or references that explain how this setup functions as intended? The router allows reserving IP addresses outside the pool, and it operates intermittently. It seems clearer to reserve them in a way that helps differentiate reserved from regular IPs—above 100 is in the pool, below 100 isn’t. This also makes adding new reserved addresses simpler without checking existing allocations. I’m not disputing your perspective, but I’d like to see the reasoning behind it. It appears to align with logical expectations, even if it isn’t explicitly stated. The router doesn’t forbid it, though it might not be the primary design. I could test using all DHCP addresses to see if it improves performance, but that would require significant adjustments and might complicate things.
You're absolutely right. It's not the way it typically functions with DHCP servers.
It was unusual for me to understand how it functioned on older router models, particularly with Linksys. That’s the way it operated. I recognize that the correct method is better suited for your needs. If you test it and it succeeds, it could simply reflect how your router handles IP assignments.
Configuration panel > DHCP Reservation (highlighted blue button near the middle of the screen)