Unicorn

Security, Network, Linux and Programming

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Netbox slow response times without internet connectivity

Date: 01 Aug 2026

This was an issue that puzzled me for a couple of hours before figuring out what was wrong. The below HTTP duration graph shows an obvious problem with the response times for netbox, taking up to 10 seconds.

Grafana dashboard showing slow HTTP response from netbox

I initially thought this had something to do with migrating the host running my Netbox service.

But after testing and validating all components used: Nginx, Redis, Postgres none of them showed signs of causing this latency.

Looking at the time this became an issue it occured to me, it was the same time I disabled internet connectivity for this server. So re-enabling internet connectivity verified what caused the issue, now I needed to figure out why it was requiring internet access.

Surprise

So as I wrote the below section I thought the issue was resolved as the response times went back to normal after setting that environment variable, but that wasn’t the case.

RELEASE_CHECK_URL

According to the docs this is disabled by default Default: None (disabled) Docs: release_check_url.

But for some reason it was default enabled in the env/netbox.env file in the netbox-community/netbox-docker repo.

RELEASE_CHECK_URL=https://api.github.com/repos/netbox-community/netbox/releases

So setting this to RELEASE_CHECK_URL=None in the docker-compose.yml fixed the issue and I can now disable internet connectivity yet again, without slow response times from Netbox

Solution

After spending quite some time and a reddit thread I discovered the SNI in the requests was api.netbox.oss.netboxlabs.com, which is being used for showing some news feed on the dashboard.

In the quest of finding a way to disable this I found ISOLATED_DEPLOYMENT which basically does what I needed.

Tags: Netbox