Occasionally, a faulty SIM card will prevent your smartphone from establishing a steady network connection. If the SIM card is removed or placed incorrectly, the same thing might happen. Removing and reinstalling the SIM card on your iPhone 8 might help rule this out as a possible reason. Here's how it's done correctly:

• Prepare a SIM eject pin or a little paper clip.
• Completely turn off your iPhone.
• On the right side of the phone, look for the SIM tray.
• Insert the pin into the little hole and gently push it out to release the SIM tray.
• Remove the SIM card from the tray and set it aside.
• Look for apparent signs of damage, such as scratches or dents, on the SIM card and the SIM tray.
• Place the SIM card back into the tray with the gold contacts facing down if there aren't any. Check to see if the notched corner is aligned.
• Contact your carrier for official advice if you see any signs of damage to the SIM card or SIM card tray.
• Turn on your iPhone 8 after reinstalling the SIM card and the SIM card tray to verify if the problem has been resolved.