03-19-2024
Router to Printer Comms: Ethernet through L2 switch with 802.1Q active on other than printer port (printer is on primary subnet).
Printer bound to IP XXX.XXX.XX.5
LAN>DHCP Server
Domain: Workgroup
IP Pool Starting = XXX.XXX.XX.100
IP pool Ending = XXX.XXX.XX.254
Lease time (sec): 604800 (7 days)
Change sleep mode on printer from 15 to 5 minutes.
Change DHCP Lease Time to 360 (6 minutes) and Apply
Check System Log - DHCP leases. Printer not there.
Network map shows Printer online
Observe System Log - DHCP leases
Strange. Only devices that are not sleeping show lease times within the 6 min range. All other (sleeping) devices show much longer DHCP lease times. And, many more devices showing on the System Log - DHCP lease screen that are not connected.
Reboot Printer
Check System Log - DHCP leases => Still no Printer DHCP Lease
Change Printer from Static IP to Automatic.
Now, printer shows in DHCP Leases screen with correct MAC-bound IP
Allowed lease time to expire => renewed, even though printer should be in sleep mode
Observed several lease time countdowns. Printer never reached 0, but renewed before lease expired.
Change Printer sleep mode to 10 minutes.
Observe System Log - DHCP leases
Printer renews lease prior to expiring. ALL other devices doing the same thing: never go to Expires = 0. All renew before 0 seconds. When renewed, all non-sleep mode devices go back to 6 min DHCP lease time. All sleeping devices have very long lease times and were not renewed when I changed the DHCP lease time from 604800 to 360 sec.
Change DHCP Lease Time to 86400 (24 hrs) and Apply
Observe System Log - DHCP leases
Device expiration times are consistant with change.
Sleeping devices still show very long Expires times but some (not all) did renew to 24 hrs.
Still showing devices in DHCP lease table that are not connected.
Connected (turned on) one device. DHCP lease for this device refreshed immediately
Turn off Guest Network Pro > VLAN 53 (2.4Ghz WiFi only).
Now, check to see if these devices vanish from DHCP leases list => ALL VLAN devices vanished
NOTE: Still one ethernet connected device (sleeping PC) still showing very long Expires time
Turn ON Guest Network Pro > VLAN 53 (2.4Ghz WiFi only).
Now, check to see if devices return to DHCP leases list => ALL returned, even devices not connected.
REBOOT Router.
Now, DHCP lease table only shows devices that are connected with proper Expires time.
Printer is not showing.
Tap on Printer scereen. Still no DHCP for Printer. But Printer shows in Network Map.
Turn printer OFF then ON. Now printer shows in DHCP lease table
Change DHCP Lease Time to 300 (5 minutes) and Apply.
Observe System Log - DHCP leases
Only online devices refreshed DHCP Expires times. Both sleeping devices did not renew lease time.
Change DHCP Lease Time to 86400 (24 hrs) and Apply
Observe System Log - DHCP leases
Sleeping devices did not renew lease times but did resume Expires time from before this change.