N1548 Web UI - Network Congestion or Lost Connection

When i login to the Web interface and stay idle for the duration of "http timeout-policy", the switch (at least the admin interface) seems to hang/stall for a couple of minutes.

The browser shows me the message in the screenshot below.
If i immediately try to reload, the browser says "ERR EMPTY RESPONSE".
When i have waited a few minutes, i can load the login page again.

During these few minutes, if i try to fetch the dell_login.html page from command line, this is what happens:

support@mgmlnx:~$ curl -kv https://mlmsw1-0/dell_login.html
* Hostname was NOT found in DNS cache
* Trying 10.10.253.10...
* Connected to mlmsw1-0 (10.10.253.10) port 443 (#0)
* successfully set certificate verify locations:
* CAfile: none
CApath: /etc/ssl/certs
* SSLv3, TLS handshake, Client hello (1):
...
* SSL certificate verify result: self signed certificate (18), continuing anyway.
> GET /dell_login.html HTTP/1.1
> User-Agent: curl/7.35.0
> Host: mlmsw1-0
> Accept: */*
>
* SSLv3, TLS alert, Client hello (1):
* Empty reply from server
* Connection #0 to host mlmsw1-0 left intact
curl: (52) Empty reply from server

And if i try to ssh into the switch during these few minutes, it does work, but its extremely slow.

FW version is: 6.6.0.2

I see this behaviour on all our N1548 switches (same FW on all of them)