When trying to ping a divice (AccessPoint) in a subnet, ping failed...

Executing in WinBox Terminal:
[admin@MikroTik] > ping 10.10.10.5 interface=ether3-WLAN-hotspot count=3
HOST SIZE TTL TIME STATUS
10.10.10.5 timeout
10.10.10.5 timeout
10.10.10.5 timeout

... but trying a arp-ping getting valid result...
Executing in WinBox Terminal:
admin@MikroTik] > ping 10.10.10.5 interface=ether3-WLAN-hotspot count=3 arp-ping=yes
HOST SIZE TTL TIME STATUS
00:1D:0F:EA:EB:65 1ms
00:1D:0F:EA:EB:65 0ms
00:1D:0F:EA:EB:65 0ms
what does this mean?
Normally I am not able to ping the destination, why succeeded the arp-ping?

Thanks a lot for help for a MikroTik-newbie

I would try disabling your firewall rules to see if something is blocking it and look at ip->routes

I'm afraid to turn off the firewall rules and nat would disconnect my VPN connection, because I administer the system away and I need the vpn connection and the corresponding nat rule.
Thanks and Best Regards, Mike.

You can leave the nat stuf... just disable in firewall filters, any icmp drops or rejects. If that sounds too dicey, just ad an entry in the firewall filter above any corresponding drops that does the exact same thing except it logs. Then enable logging for firewall and see which rule is doing it. Use the prefix to distinguish between multiple logging entries in your firewall. Also, you could post your firewall here and see if anyone can spot something.

After using DHCP instead of assgning a static ip the ping works and the machine is reachable (after defining a firewall rule).
But I have no idea why not while having a static ip ??
Thanks and best regards, Mike.