Privacy Error Won't Go Away

[#1]

Morning. On my mac, I keep getting a Privacy Error on lots of non-coorporate sites, so Facebook, BBC, Google all working well, but smaller businesses, forums etc get this privacy message:

NET::ERR_CERT_DATE_INVALID

It's happening on Chrome & Safari. NB. Other connected devices are fine.

I have cleared cache/history etc, I've changed DNS to google on my mac, I've restarted my mac, reinstalled Chrome, checked updates, I've reset the router...everything that I've read about. I'd be most grateful for any thoughts. Thanks

Moderators Note: All caps title removed as per Forum rules

[#2]

Which version of macOS are you on?

[#3]

First couple of bits I'd check is that the time is correct on your mac.  The second place I'd look is at any antivirus/antimalware type programs.  I've seen before with Avast (and there was another who's name I can't think of) that the certificates are replaced with their own on many other sites.

[#4]

I'm on El Capitan

[#5]

Thought you might be, have a look at https://mjtsai.com/blog/2021/09/24/some-web-sites-will-stop-working-with-el-capitan-and-older/

Can you not update beyond El Capitan?

[#6]

Thanks but it's not either of those.

[#7]

Ironically, I can't open that link on my mac! but I'll look at it later, thanks, worth a try. 

[#8]

Moderators Note

This topic has been moved from ADSL Broadband to Tech Help