The Netgear Nighthawk M2 Mobile Router (MR2100-100EUS) is a 4G LTE Advanced Pro mobile router that is compatible with various LTE bands. Here are some important points that might answer your question:

## Compatibility with Sunrise
The router supports a wide range of LTE bands, including LTE 700/800/900/1800/2100/2300/2500/2600 MHz.
Sunrise, as a Swiss telecoms provider, typically uses the 800, 1800, 2100 and 2600 MHz bands. As the Nighthawk M2 supports these bands, it should generally work with Sunrise.

## Performance problems
If the router is very slow despite a properly functioning SIM card (e.g. 10 minutes to load a website), several factors could be responsible:
- Network coverage and signal strength: check whether the signal strength of the mobile network in your area is sufficient.
- Configuration and settings: Make sure that the router and SIM card are configured correctly. Use the NETGEAR mobile app to check the settings and network connection.
- Firmware and software: Make sure that the router's firmware is up to date, as updates often contain performance improvements and bug fixes.

If these steps do not help, it may be useful to contact Netgear or Sunrise support for specific assistance.