Safari seld signed certificate error : cannot connect to web gui

Hi all,

I have an XG310 Cluster with firmware 16.5 and a big problem with my safari.

After a fresh new installation of MacOS High Sierra, suddenly Safari won't connect to XG web gui console https://192.168.x.y:4444/

It's a self signed certificate problem, even If I enable the trust of the certificate through the safari two step process in the web page ( as for others https websites ) , it continues to ask me in an endless loop this two "questions" to enable the trust to XG web gui URL address.

In the keychain I enable the trust of the appliance with no luck, and if I enable the trust for everything in that certificate, the URL return an http 400 error "Bad request". 

I know that there are new safari security policies, I tried to get around them but without success, clearing cache manually , removing cache.db and so on...

I read here in this community the topic ( https://community.sophos.com/products/xg-firewall/f/authentication/90839/safari-can-t-establish-a-secure-connection-to-xg-firewall---chrome-ff-ok ) but it was of no help to me.

Any ideas?

The bad request error it's weird.

One last thing. Firewall IP address is not "DNS mapped" , there is no name IP record in our DNS system.

I tried to map our firewall IP address to a name in our DNS server ( Active Directory domain DNS ) and with the name address url it works...

But I want to access to the appliance URL with IP not with address...

One last thing. My office colleague , same operative system (iMac with High Sierra ) same exact problem...

Any ideas???

best regards to all,

Simone

Simone