Unfortunately, I can’t simplify the network, the router from ISP can’t be configured as Bridge.
I ask if I could have an ONT separated (since the router is connected directly to Optical) and the answer was a round NO.
Also they not given away the settings to configure the Firewall with public IP.
Botton line; ISP’s router gets the public IP and NAT to 193.*, best possible thing, was to configure the Firewall as DMZ destination and control all packages at the Firewall ( ISP’s router can be hacked by anyone, the “how to” is on the web … you don’t even have to go to darkweb)
However, looking at your explanation, it did made sense, I had activated the DNS resolver for some trials, at the time didn’t impact with the sync function, but was clearly impacting with the download.
I disabled the resolver … because I don’t actually need it … and is now working.
Have a look on the answer from @MovieFan.Plex, at least on my case guide me to the solution.
