IPv6 name resolution fails

My inteet coection is provided by my university

Case 1

My University -> Laptop direct coection

Everything works fine here

Case 2

My University -> Netgear WNR614 with DHCP -> Laptop

IPv4 works fine, curl -4 url requests are perfect, but curl url times out / takes too long to load

Case 3 My University -> Netgear (with DHCP server off) -> Laptop

Everything works fine as usual.

What might be the issue here? (The DNS servers provided by my university are local addresses)

Here is the diagnostic result

Test with IPv4 DNS record       ok (0.766s) using ipv4
Test with IPv6 DNS record       timeout (16.490s)
Test with Dual Stack DNS record ok (0.854s) using ipv4
Test for Dual Stack DNS and large packet        ok (0.803s) using ipv4
Test IPv4 without DNS       ok (0.816s) using ipv4
Test IPv6 without DNS       bad (0.009s)
Test IPv6 large packet      timeout (16.439s)
Test if your ISP's DNS server uses IPv6     timeout (16.430s)
Find IPv4 Service Provider      ok (2.072s) using ipv4 ASN 55824
Find IPv6 Service Provider      timeout (16.999s)