Sophos endpoint client is not able to upgrade while Unified Agent is installed
Unified Agent is blocking some or/all the Sophos endpoint client domains
The situation can be solved by adding the Sophos endpoint domains in the bypass list by accessing the threatpulse portal account> Service>Network>Bypassed sites> Bypassed Domains>Add bypass Domain(s)
Add all following domains;
*.sophos.com
*.sophosupd.com
*.sophosupd.net
*.sophosxl.net
ocsp2.globalsign.com
crl.globalsign.com
You can also find the domains by accessing the following link: https://community.sophos.com/kb/en-us/121936