You are my "signature" read? I'm not talking about the "Donate", but about the fact that the above - "please include the following minimal information ...".
Reboot the NAS and refer to HTTP instead of HTTPS. I am absolutely sure that the problem is not an add-on. For example, in the DNS-327L latest firmware, HTTPS standard port 443 was replaced with port 4443. The options are many of your problems!