Based on historic knowledge there was no ipv6 infrastructure and no interest in correcting that. There is a very “MURICA” stance on ipv6 a.k.a not an us problem. You need ipv4 routing.
I would also recommend updating the mirrors to “https” which will point you at their newer servers.
His system has IPv4, but IPv6 was never intentionally disabled or enabled. So it is likely enabled and not specifically configured. I believe that is how a default FreePBX 15 system is.
A current FreePBX 16 system does not use https. Granted this was at one point FreePBX 14 (or maybe even 13) that has been upgraded to 16 over the years. So maybe a new FreePBX 16 install would be different.
edit: This is not hte OP’s system, this is mine.