3cx won't activate (Debian 10)

[cxlabs]

Hi, so I've tried everything (famous last words): Setting the DNS server to 8.8.8.8, deactivating ipv6 altogether, even hacking the hosts file. There is no firewall, neither local nor infront of the machine. I keep getting this message:

3CX failed to establish a TCP connection to activate.3cx.com.
Ensure that the local or border firewalls are configured to allow outbound traffic to activate.3cx.com

nslookup & ping all yield proper results:

# ping activate.3cx.com
PING activate.3cx.com (104.18.15.54) 56(84) bytes of data.
64 bytes from 104.18.15.54 (104.18.15.54): icmp_seq=1 ttl=57 time=9.53 ms

# nslookup activate.3cx.com
Server: 8.8.8.8
Address: 8.8.8.8#53
Non-authoritative answer:
Name: activate.3cx.com
Address: 104.18.15.54
Name: activate.3cx.com
Address: 104.18.14.54
Name: activate.3cx.com
Address: 2606:4700::6812:e36
Name: activate.3cx.com
Address: 2606:4700::6812:f36

 

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Make sure your 3CX is updated to the latest build.