DHCP is convenient because devices get an address automatically, but that convenience becomes a problem the moment you need a firewall rule, port forward, or bandwidth limit that targets one specific device. A dynamic lease can change the next time it renews — and any rule pointed at the old address silently stops working, with no error to tell you why.
Find the device's MAC address
Check the current dynamic lease list to find the device you want to pin down:
/ip dhcp-server lease printOption A — add the static lease directly
If you already know the MAC address and the IP you want it to keep, create the lease in one line:
/ip dhcp-server lease add address=192.168.88.50 mac-address=AA:BB:CC:DD:EE:FF server=dhcp1Option B — convert an existing dynamic lease
In practice this is usually easier: let the device get a dynamic address once, confirm it's the IP you want to keep, then make that lease permanent:
/ip dhcp-server lease make-static [find address=192.168.88.50]Optionally give it a name
Add a comment to the lease so it's obvious what the device is six months from now, when you're looking at a list of thirty leases and can't remember which one is the office switch.
Why do it this way
A static lease keyed to the device's MAC address gives you an IP you can build on — firewall rules, port forwards, and simple queues that target that address stay correct even if the device is unplugged for a month and rejoins the network later. The alternative, hardcoding a device's current dynamic IP into a rule and hoping it never changes, works right up until a lease expires at an inconvenient time and something you depend on quietly stops routing correctly.
How MoniTik helps
MoniTik already tracks every device and interface it monitors, which gives you a live inventory of what's actually on the network without maintaining a separate spreadsheet of MAC-to-IP mappings by hand. If you're setting static leases specifically so you can remember which address belongs to which device, MoniTik's device list is solving the same underlying problem from a different angle.
Santiago spends his days on rooftops and in racks, keeping MikroTik links online for local ISPs.