The issue appears to be DNS, or more specifically DNSSEC on the ka2ddo.org domain. This would explain why it works for some and not others. Not all DNS revolvers support DNSSEC.

With DNSSEC disabled, ka2ddo.org resolves fine.

With DNSSEC enabled, ka2ddo.org doesn't resolve in DNS.

Andrew, I would suggest you verify the DNSSEC settings with your domain registrar and DNS provider to make sure everything matches up.

See also this site for troubleshooting:

Hope that information is helpful.

Kevin
KB9MQU

------- Original Message -------

On Sunday, February 20th, 2022 at 15:24, Andrew P. <andrewemt@...> wrote:

> OK, this is getting strange. I know I renewed my domain name and installed my new SSL certificate for the site. And (rather than use my house network where the server is connected), I used my AT&T mobile hotspot on a laptop to get Internet access, and over that path I was able to see my website.
>

> So, something on the path of every user having difficulty accessing the site must be either:
>

> 1. not looking up the domain name correctly
>

> 2. caching the expired certificate so as to say the site isn't trusted.
>

> I did find it amusing to notice, during the 5 days the expired certificate was still in use, the only users who still successfully accessed my website were webcrawlers and attackers. Apparently both disable failing an SSL connection just because the server certificate is expired.
>

> So here are the checks I'd like everyone who is having difficulties to do:
>

> 1. Try to look up my domain name with the nslookup command on your local computer. From a shell, DOS prompt, or Terminal window (depending on your O/S), enter the command
>

> nslookup .
>

> You should get an answer back of 71.162.157.26. If you don't, then someone is caching a negative lookup (because somehow the auto-renewal of my domain name was turned off, so there may have been a few hours when my domain name wasn't in service, although there shouldn't have been).
>

> 2. Try browsing the URL
>

> This should get you to my website without using DNS or SSL. If that works, then there is caching of the bad certificate lookup that needs to be cleared. You should clear your browser cache and try the normal URL again. If that fails, then you are using a proxy between you and the rest of the Internet that is caching the expired certificate lookup failure, rather than going to my webserver and trying again. Note that these proxies can be inserted without your consent or knowledge; the most common sort is on a hotel's Wifi, to ensure you are a paying guest before being allowed to use their Internet service.
>

> Let me know what you find out with these tests.
>

> Also, if you are getting the failure within YAAC, shut down YAAC completely and restart it. The Java runtime has a cache, too, but the cache will be discarded when you stop the Java runtime.
>

> Hope this helps.
>

> Andrew, KA2DDO
>

> author of YAAC and webmaster of
>

> ________________________________________
>

> From: [email protected] [email protected] on behalf of Bob Evans bob9750@...
>

> Sent: Sunday, February 20, 2022 2:51 PM
>

> To: [email protected]
>

> Subject: Re: [yaac-users] YAAC
>

> Hi
>

> Just done a fresh install of YAAC on a new Ubuntu system and getting java error 'unable to receive files from server ......etc'
>

> Also can't access ka2ddo homepage from other systems with 'site can't be reached' error
>

> Bob
>

> On Sat, Feb 19, 2022 at 7:18 PM Andrew P. <andrewemt@...:andrewemt@...> wrote:
>

> Looks like you typed Kilo Alpha 2 Delta Delta Zero instead of Oscar. :-)
>

> The site is up; I checked from at least 3 places. However, if your browser or proxy server is caching the stale certificate, you might need to do a Shift-refresh of the page.
>

> Andrew, KA2DDO
>

> ________________________________________
>

> From: yaac-users@...:[email protected] <yaac-users@...:[email protected]> on behalf of Richard Beggs <richard.n0eb@...:richard.n0eb@...>
>

> Sent: Saturday, February 19, 2022 7:07 PM
>

> To: Andrew Pavlin
>

> Subject: [yaac-users] YAAC
>

> Still can not reach ka2dd0.orghttp://ka2dd0.orghttp://ka2dd0.org?
>

> --
>

> Thank You and God Bless [¡`]
>

> Richard
>

>