Thank you so much for your time!
I am sorry, I'm not the sharpest pencil in the IT pencil box, thats why I have chosen Apple :)
Now back to topic, I changed the Off (bridge) mode to DHCP and NAT. After that I can see the LAN connected IP address, and it is not the same as with the other devices (as you wrote). It is shorter with 2.1.3.1 set of numbers, where 3 number set is the same as other addresses.
With the IPv6 there is no setup for me to find AirPort Utility, Internet.
IPv6 DNS Servers: -empty
: -empty
Internet Options;
Configure IPv6: Automatically
IPV6 Mode: Native
IPv4 thou has address.
Arlo tecnical support sent me an other answer;
Before troubleshooting make sure that gates 80, 123 and 443 are open on your router.
Also, that DHCP-settings are active.
Please, be aware that the base station has to be connected directly into router (port 1 or port 2)
If it could help, then I would restore the internet settings to the default and start again, but I have not found that option for Airport. I would not like to reset the AP to the factory reset, as I have there 2Tb of everything. As I found out that data will be lost with this factory reset. I have made soft reset to AirPort.