RealPresence 300 and 500 unable to locate the server for calendaring

[Adam in DC]

I have reviewed the FAQs in this forum and am hoping for a suggestion that will put me in the right direction.

I have two RealPresence units in Washington and two in London.  We were recently fortunate to acquire 4 RealConnect licenses through Polycom's new promotion.  After a bit of work, I was able to successfully connect the 2 DC units not only to 365, but ultimately, One Touch Dial OTD.  We have successfully tested a Microsoft Teams call in DC using a 310, 500 and desktop units via RealConnect.  It works

Unfortunately, in my London location, I am unable to successfully connect to either 365 or OTD in the calendaring service.  My 500 is running 6.1.5.  Can I assume this version supports 365 and/or OTD?  I don't want to upgrade the unit until I am physically in front of the unit and can do so via USB - which I find to be better than via the web.

If it's not the version of the OS I have checked the following items:

• I've checked and updated the DNS for our newest internal DNS servers
• I've checked and updated the network name
• I've added the following objects to an allowed address list for video conferencing in our Firewall in London
  • outlook.office.com
  • outlook.office365.com
  • smtp.office365.com
  • old.plcm.vc
  • t.plcm.vc

And yet I still cannot connect the calendaring service to either 365 or OTD. 

I have also checked the user name and password for the account and made sure the naming convention was correct. 

This feels to be a firewall issue - what other addresses - either named or IP - must I add to the whitelisted group for the 300 or 500 to talk to their respective calendaring services - either in 365 or OTD.  Thanks. 

[Adam in DC]

For those that might be interested, it turns out that the unit in London we received from Polycom and/or their distributor and a "security profile" set to "Maximum."  This basically meant that it couldn't connect to anything.  Apparently, their normal profile is "Low."  When I changed it to Low - the calendaring service worked. 

Unfortunately, changing the security profile blew away all of the user names and passwords to login to the unit - so it's orphanned and needs a factory reset.  But the OTD OneTouch Dial works.