Lot of details matter. Not sure i can list all of them here. But at least some, router - some kind of internet router or it is CNC router?
If internet, small SOHO router like "soapbox" NAT with wifi or some beefy cisco router? Does it have PoE? Does it have ethernet devices connected by long cables(especially outdoor)? Can surge come over this cables?
Surge supressors useful only when threat factors is clear and they are installed in proper places.
For example, if you installed protection on the UPS mains, and the EMP comes from one of the connected ethernet devices, this protection is useless, and may even aggravate the situation.
Factory supplied SMPS all different, some are bad quality, some cheapo might leak surges over noise filtering caps, and etc.