> For the complete documentation index, see [llms.txt](https://indoor.router.works/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://indoor.router.works/ezr23/diagnostics.md).

# Diagnostics

- [Internet & IP](https://indoor.router.works/ezr23/diagnostics/internet-and-ip.md): Run a first quick Internet access test to check Internet connectivity.
- [Changing Web Port](https://indoor.router.works/ezr23/diagnostics/internet-and-ip/changing-web-port.md): Guidance of how to change the Web GUI interface port on the 4G router.
- [Modem Connection](https://indoor.router.works/ezr23/diagnostics/modem-connection.md): Guidance to verify the physical connections and virtual interfaces of the mobile modem device.
- [Verify SIM Card](https://indoor.router.works/ezr23/diagnostics/verify-sim-card.md): Verify the SIM card installation and registration on the cellular networks.
- [Signal Strength](https://indoor.router.works/ezr23/diagnostics/signal-strength.md): Guidance to check the accurate cellular signal strength information receiving on the EZR23 router.