Joined: 18 Mar 2013 Posts: 21 Location: Sanford, NC
Posted: Sun Apr 16, 2023 2:44 Post subject: DHCP not providing IP/DNS addresses
I have static IP addresses on all my devices; but recently noticed a visitor could not get a DHCP IP address or DNS info. I've updated my DD-WRT to r52330 and config appears correct. The client can connect to the WiFi; but not the Internet. Not sure when I last had DHCP working; but other than updating firmware, had no reason to change any DHCP settings. Has anything changed in the firmware that may require changes to the config. Been searching for hours and can't find anything.
Static IP addresses or static leases? How many static leases vs. DHCP pool size? Are you using a separate AP for guest wifi access, and if so, have you configured a separate instance of dhcp for said interface (usually a VAP)? _________________ "The woods are lovely, dark and deep,
But I have promises to keep,
And miles to go before I sleep,
And miles to go before I sleep." - Robert Frost
"I am one of the noticeable ones - notice me" - Dale Frances McKenzie Bozzio
Joined: 18 Mar 2013 Posts: 21 Location: Sanford, NC
Posted: Sun Apr 16, 2023 3:27 Post subject:
Super simple setup: just DHCP pool 192.168.1.50 for 10 clients. Used to work; but I have no idea when it quit working since all my clients have non-DHCP static addresses; not leases. Just 5GHz and 2.4GHZ SSIDs; no guest network.
Joined: 18 Mar 2014 Posts: 12875 Location: Netherlands
Posted: Sun Apr 16, 2023 12:50 Post subject:
Modern clients use random MAC addresses so your clients might not always use their designated static leases.
Check what is using the DHCP on Status/LAN page.
Furthermore standard Lease time is 1440 min (Basic Setup page) and a lease is only removed after the lease time is expired so with only 10 slots and a lease time of 1440min it is possible you exhaust your slots.
You guest users also might have random MAC addresses so if they go away but shortly after that return they use an other MAC address and get a different lease but the old lease is still there until it expires.
Joined: 18 Mar 2013 Posts: 21 Location: Sanford, NC
Posted: Sun Apr 16, 2023 14:29 Post subject:
Restating to bring the discussion back to "Super Simple" setup:
I have only static clients which are not in the DHCP pool range and are not static "leases"; they are permanent IP assignments, configured within clients only; and all work as expected.
The DHCP pool is intended for colleagues/visitors with no static leases; they just appear on the network as new devices, simply wanting DHCP data.
Recently, visitor devices (laptops/phones) connect to WiFi expecting a DHCP-provided IP address and DNS info; but get nothing.
Some, not all, devices can be manually configured with IP & DNS; on one phone the other day, could not find how to change its config from DHCP to manual -- so it could only connect to WiFi; but not communicate.
DHCP used to work months ago; but quit sometime before 5 weeks ago when I first noticed this issue -- just now researching why, due to time constraints.
The versions I've used in the past year: r48141, r48567, r49113, r49139, r49492, r49838, r50308, r50500, r50906, r51043, r51140, r51729, r52330 on LinkSys WRT3200ACM
Status/LAN/DHCP Clients:
Samsung_A21_2 192.168.1.22 FE:79:A6:7F:0B:8F 0 days 12:14:25
This is my phone which is configured with a permanent static on the 5GHz band/SSID (so not in this list or pool). Re-configured it from permanent static to DHCP on the 2.4GHz band/SSID -- whether the IP in DD-WRT is defined as a static lease, or set to use the 192.168.1.50 pool of 10 addresses; it does not get IP/DNS even if it appears in the list (above).
Slots can't exhaust if foreign devices appear at most once a week; never simultaneously.
>So increase the number of slots and/or decrease lease time.
Setting Lease Expiration to 5 minutes does not help -- see above.
Hmm... Surely, DHCP wasn't changed to respond to guest interfaces only; was it? I'll have to test out this theory when I have time later...
Visual aids (screenshots) of applicable pages / sections of the webUI speak volumes over text and repeated argument. _________________ "The woods are lovely, dark and deep,
But I have promises to keep,
And miles to go before I sleep,
And miles to go before I sleep." - Robert Frost
"I am one of the noticeable ones - notice me" - Dale Frances McKenzie Bozzio
The versions I've used in the past year: r48141, r48567, r49113, r49139, r49492, r49838, r50308, r50500, r50906, r51043, r51140, r51729, r52330 on LinkSys WRT3200ACM
Hardware reset, factory defaults or nvram erase && reboot manually reconfigure do not restore from old backups.
If you can reproduce the problems, then show relevant or applicable settings from defaults for others to diagnose.
