Intermittent connection error to local webservers, when using Opera

1

I am a little bit unsure in which category this would fit best, so I put it here.

I have this really odd problem with my webservers that keeps happening, mostly during evenings, when I’ve been at the PC for a while. Although I can’t say for certain that time of day or anything like that has a role in this.

I use Opera as my daily web browser, and at some point during the day, when I’m trying to access my webservers, I start to receive an error ERR_CONNECTION_TIMED_OUT. This may happen to only one of my webservers, a few of them, but most often all of them at the same time. This problem may also resolve itself after a while.

However, if I try to reach the same webserver from a different browser, like Firefox or Chrome, there is no issue. The issue stays isolated to the Opera browser it seems. The webservers do have an nginx reverseproxy infront of them. And when this problem occurs, I don’t see any incoming requests in the logs on the reverseproxy from the Opera browser, suggesting that the problem occurs before being redirected by the nginx server? I also don’t see any error logs or similar anywhere.

I was able to find some potentially interesting stuff from the dev console in the browser, provided in a screenshot below.

If anyone has got any input to this, on how to continue troubleshooting, or things to check, that would be greatly appreciated! And if something in this brief explanation is unclear, please let me know and I will try to give more information and context.

Screenshot from the dev console in my Opera browser when trying to reach my Grafana server:

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2

Have you tried to reinstall opera? Or try an older version to see if this problem is on a newer version?

Are you using any kind of extensions or proxies?
Maybe try a vanilla install?

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3

Reviving this one since I think I’ve finally figured out the issue.

It seems like Opera isn’t respecting the OS DNS settings, but defaults to resolving the public A records (pointing to my Public IP) instead of my local A records (Pointing to my internal reverse proxy). And since I didn’t have any active port forwarding the packets got droppet at the WAN interface.

I’m currently in the process of properly implementing Split-horizon DNS with a separate reverse proxy for internal clients and external clients, which should hopefully “solve” this issue.

The question still stands though, why Opera isn’t using the local DNS server as is configured on the OS, like Firefox does?

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I wonder if it’s DNS over HTTPS (DoH) settings in Opera, or perhaps using the built in VPN it has.

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DoH is disabled, at least it shows that way in the Opera settings :laughing: But pinging my local domain (that also has a public A record) from opera://net-internals/#dns does return my public IP

6

Have you that “data saver” thing off?

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What I ended up doing was that I configured a firewall rule in my Unifi Gateway to block port 80 and 443 on my public IP from clients within my local subnet. That way, Opera is being forced to use the IP of the local CNAME record, I think. Anyways, it’s been working great since I made that firewall rule :smiley: