In the last couple of weeks, I've started getting this error ~1/5 times when I try to open one of my own locally hosted services.
I've never used ECH, and have always explicitly restricted nginx to TLS1.2 which doesn't support it. Why am I suddenly getting this, why is it randomly erroring, then working just fine again 2min later, and how can I prevent it altogether? Is anyone else experiencing this?
I'm primarily noticing it with Ombi. I'm also mainly using Chrome Android for this. But, checking just now; DuckDuckGo loads the page just fine everytime, and Firefox is flat out refusing to load it at all.
Firefox refuses to show the cert it claims is invalid, and 'accept and continue' just re-loads this error page. Chrome will show the cert; and it's the correct, valid cert from LE.
There's 20+ services going through the same nginx proxy, all using the same wildcard cert and identical ssl configurations; but Ombi is the only one suddenly giving me this issue regularly.
The vast majority of my services are accessed via lan/vpn; I don't need or want ECH, though I'd like to keep a basic https setup at least.
Solution: replace local A/AAAA records with a CNAME record pointing to a local only domain with its own local A/AAAA records. See below comments for clarification.
Any chance you are both accessing your services locally with a local DNS, and publicly with something like Cloudflare?
I do have external acces to Ombi via cloudflare; but the device I'm seeing this problem on is permanently connected to a VPN hosted from the same server machine as ombi/nginx with 'block all connections without VPN' enabled. And this testing has been done from within the same LAN.
It should never see/reach cloudflare for this service.
/edit; I've also disabled 'use secure DNS' in chrome. I host a local DNS within that lan/vpn network.
Can you verify with wireshark that the traffic is only going through your lan? I'm not hip enough for nginx but I used to have to run apache under gdb all the time to trace random errors from the server. That would be next, if the traffic is really local.
I'll look into that next if what I've done doesn't work. (see other comments)