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A user cannot access my site

Splinter

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on: June 20, 2019, 02:07:22 PM
Suddenly one of our  members can't access my forum in any browser. He's tried Edge, Opera, Chrome and Firefox.
This is the site in question https://www.argentinaexpats.org
I've double checked my IP blacklist and he's not been blocked accidentally.
I also use  User IP Log plugin and added him to the whitelist for double accounts and I've also checked his status in the user groups. Everything checks out normally.
The message he's receiving from all browsers is that the website can't be found, although the website is clearly up, but not for him.
He can't access from his phone either, so I'm assuming that he must be blocked in some way.
I asked him to ping the site from his location and no errors were reported.
As far as I know, he is the only person not able to reach the site, but one does wonder if this is isolated or not.

It's been suggested that the connection was dropped by the remote server, but way before reaching the forum software.
"This is likely the result of some kind of firewall or filtering that terminates the connection before the webserver (or its modules) are even involved."
Anyone got any ideas on this one?


Wooster

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Reply #1 on: June 20, 2019, 03:52:48 PM
Ask him to check his DNS settings and also clear his caches (phone and pc)

Best DNS servers to use are Google
8.8.8.8
&
8.8.4.4


Splinter

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Reply #2 on: June 20, 2019, 05:27:54 PM
He can now get access on his phone which is through a different provider, so that means our software isn't blocking him.
He cleared his caches the other day.
I've asked him to change his DNS servers as suggested and also to contact his ISP.
Edit
But what's puzzling is why just the one site should be the problem.
« Last Edit: June 20, 2019, 06:30:00 PM by Splinter »


Wooster

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Reply #3 on: June 21, 2019, 07:38:25 AM
If his DNS cache is corrupted it won't be able to resolve the address, since it uses the cached entry first.
If there's no entry in the cache it then goes to the DNS host specified for the adapter, then on the router if that fails.

There's a coomand for that.
Pretty sure it's
ipconfig /flushdns


Splinter

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Reply #4 on: June 25, 2019, 08:10:03 PM
I did flush dns and netsh int ip reset to no avail
The only way he can access the site is using Opera's own VPN which is weird. It's the only site he can't access, so I've suggested he talk to his isp.
EDIT
His ISP hasn't detected any issues with the url, so I'm scratching my head now.

« Last Edit: June 26, 2019, 06:42:54 PM by Splinter »


Wooster

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Reply #5 on: July 16, 2019, 08:28:39 PM
Does he have some sort of proxy thing going on?
(The Opera VPN is more a proxy than a full VPN service)
Have a look at using the traceroute (tracert.exe) command to see where it's falling down.


Splinter

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Reply #6 on: July 16, 2019, 11:02:34 PM
I'll try that next, thanks Wooster.
I did access his laptop through Team Viewer, but couldn't find anything untoward. And I know he wasn't using the built-in VPN with Opera, which I only ever use when I need to.
I'll get back...


Splinter

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Reply #7 on: July 17, 2019, 01:26:18 PM
The user now says he can access the site through Chrome perfectly well, although Chrome wouldn't let us last week.
Good news, but I hate it when i don't know the actual reason!


Wooster

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Reply #8 on: July 17, 2019, 04:29:28 PM
I still suspect a bad DNS server.
If he's still using his ISP's it could be a bit flaky.

Even if he changed it on his machine, his ISP might still enforce the use of their own through their hardware.


Splinter

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Reply #9 on: Today at 02:16:19 PM
he spoke to them and they said there were no problems on their end. Mind you, sometimes things get lost in translation.