Ok, thank you very much for help. Will do it as soon as i get to computer.
Do it correctly, this do not need to specific the interface.
:if ([/ping 1.1.1.1 count=10] = 0) do={/ip dhcp-client release [find]}
Do not execute ping too often, or you risk to be putted sooner or later on blacklist…
Ok, now i set this:
:if ([/ping 1.1.1.1 count=5] = 0) do={/ip dhcp-client release [find]}
in system/schedule
admin@MikroTik] > /system/schedule print
Columns: NAME, START-DATE, START-TIME, INTERVAL
NAME START-DATE START-TIME INTERVAL
0 DHCP Renew apr/23/2022 15:32:24 59m
i think count=5 should be enough and interval is 59 minutes.
Thank you all for help.