Very strange - cannot reach some sites with 10.52...

Very strange - cannot reach some sites with 10.52...

I'm using Opera 10.52 build 6325 on: Linux Debian 5.0 / GNOME 2.22/ i386 / kernel 2.6.32

Sometimes, some sites can't be reached from this Opera 10.52 It gives me "Could not connect to remote server" message...
Up to now, I've found that this issue affects this sites: http://debian.org , http://releases.ubuntu.com , http://konzum.sk
(I could not figure out, what do they have in common...)

From my Opera 10.10 they are always reachable, but from 10.52 they sometimes are and sometimes not. Usually, it lasts only a few hours and then they are reachable again, but I haven't managed to see any reason for this.

I tried clearing the cookies, deleting all the private data, cache, disabling the urlfilter, disabling the plugins, javascript, restarting the PC, restarting the networking, and still nothing. I also tried clean install, but nothing helps. After some time, this issue just strangely disappears and then, again after few hours, this issue is back... I was also thinking whether this isn't problem of my internet provider, but on my Opera 10.10 and Firefox, these sites are always reachable...

I also don't use any userJS or widgets...

Does anybody have any ideas?

(I've also reported this as DSK-296041)

This is what DragonFly shows me on 10.52:

Raw request
GET / HTTP/1.1
User-Agent: Opera/9.80 (X11; Linux i686; U; en) Presto/2.5.24 Version/10.52
Host: debian.org
Accept: text/html, application/xml;q=0.9, application/xhtml+xml, image/png, image/jpeg, image/gif, image/x-xbitmap, */*;q=0.1
Accept-Language: sk,en;q=0.9
Accept-Charset: iso-8859-1, utf-8, utf-16, *;q=0.1
Accept-Encoding: deflate, gzip, x-gzip, identity, *;q=0
Connection: Keep-Alive, TE
TE: deflate, gzip, chunked, identity, trailers

Raw response
Request in progress

===================================================
This is what DragonFly shows me on 10.10:

Raw request
GET / HTTP/1.1
User-Agent: Opera/9.80 (X11; Linux i686; U; en) Presto/2.2.15 Version/10.10
Host: www.debian.org
Accept: text/html, application/xml;q=0.9, application/xhtml+xml, image/png, image/jpeg, image/gif, image/x-xbitmap, */*;q=0.1
Accept-Language: sk,en;q=0.9
Accept-Charset: iso-8859-1, utf-8, utf-16, *;q=0.1
Accept-Encoding: deflate, gzip, x-gzip, identity, *;q=0
Cache-Control: no-cache
Connection: Keep-Alive, TE
TE: deflate, gzip, chunked, identity, trailers

Raw response
HTTP/1.1 200 OK
Date: Wed, 28 Apr 2010 12:03:13 GMT
Server: Apache/2.2.9 (Debian) mod_perl/2.0.4 Perl/v5.10.0
Content-Location: index.sk.html
Vary: negotiate,accept-language,Accept-Encoding
TCN: choice
Last-Modified: Sat, 24 Apr 2010 11:37:38 GMT
ETag: "2acc878-39b7-484f9f8848480"
Accept-Ranges: bytes
Content-Encoding: gzip
Content-Length: 4964
Keep-Alive: timeout=15, max=99
Connection: Keep-Alive
Content-Type: text/html
Content-Language: sk

===============================================

The only difference I see between the requests is this line missing from the first log:

Cache-Control: no-cache


And my HIstory, Cookies, Security and Network settings on both Opera installations are the same.

Can this issue have something with: Caching of URL redirects? (see: http://my.opera.com/community/forums/topic.dml?id=403991 )

For example, now the sites works also on my 10.52 (but I'm afraid that in a few hours they won't again)...
So I've looked to the DragonFly and guess what. The line:

"Cache-Control: no-cache"

Was also on Opera 10.52 http request this time.

Can anybody see, what's happening here? Or is it everything normal?

I've just confirmed this issue on the newest Opera 10.53 linux build at my schoolmate's computer (running Ubuntu 9.04, i386). So at least I know, that this issue is not caused by bad network configuration (or installation of Opera 10.52) on my PC.
However, on Windows PC of my other fellow, this bug wasn't confirmed.

Also on 10.10 for linux these sites (i.e. debian.org) work normally.

Now the question is: could this be only the issue of our ISP (somehow interfering only with Opera 10.5x and only in specific time), or not?
I'll see this during the weekend (returning from college) and will report it here...

In the meantime, is there anybody running the Opera 10.5x linux version, that can confirm (or not) this issue, please? (Because of the random character of this issue, it is important to test it few times during the day, with interval of about few hours between the individual tests). And you can also check the network things with DragonFly...

I'll be thankful.