I got the same in my log after setup, I could see from the IPs they where "local" and originated from my ISP, but I stopped services I didn't need and made "stupid" firewall filters that solved the login attempts, I did as you describe find solution for a specific issue hence making "stupid" filter
.
User Zerobyte helped me with "correct" filter so my "stupid" but working filter got changed and simplified.
But basic I stopped services I didn't need and have the following firewall filter:
0 chain=input action=accept connection-state=established,related log=no log-prefix=""
1 ;;; Blocked Netflix adresser TV stue
chain=forward action=drop src-address=192.168.1.201 dst-address-list=Blocked Netflix log=no log-prefix=""
2 ;;; Adgang til Router fra Interne IP
chain=input action=accept src-address-list=Interne_IP log=no log-prefix=""
3 ;;; Disable ICMP
chain=input action=drop protocol=icmp in-interface=internet icmp-options=8:0-255 log=no log-prefix=""
4 ;;; Adgang til swich fra WAN
chain=forward action=drop dst-address=192.168.1.254 in-interface=internet log=no log-prefix=""
5 chain=input action=drop log=yes log-prefix=""
0 an 5 is the basic, 3 disable ICMP/ping from WAN. 1,2 and 4 is my own madness.
The services:
Flags: X - disabled, I - invalid
# NAME PORT ADDRESS CERTIFICATE
0 XI telnet 23
1 XI ftp 21
2 XI www 80
3 XI ssh 22
4 XI www-ssl 443 none
5 XI api 8728
6 winbox 8291 192.168.0.0/24
192.168.1.0/24
192.168.2.0/24
192.168.3.0/24
7 XI api-ssl 8729 none
And when I look at it it seems that firewall filter 2 is not needed as I have LAN IPs on the service WinBox, hopefully Zerobyte sees this post and answers
And searching for security related to RB I found out that, RB router that has been "hacked", is done in the first 10 minutes of online time if you did not set a password and/or changed the std. user.