BuddhaSkoota :
If you believe there is adequate protection inside a modem itself, I only suggest you perform a simple web search on the number of modems damaged by hazardous voltages due to surges or lightning. In short, there is little to no protection provided by a modem's circuits.
To challenge reality, one must intentionally misrepresent. Nobody said modems have complete protection. But modems have adequate protection - superior to what those near zero protectors claim.
All modems have serious protection. Protection that means most transients are only noise. And defined by numbers. Protection is so good that a potentially destructive transient might exist only once every seven years. A modem must withstand more than 500 volts on phone lines without damage. An industry standard that existed before PCs existed.
Concern is a rare surge that can overwhelm that protection. Adjacent protectors (ie APC or Cyberpower) do not even claim to protect from that type of transient.
How do phone companies all over the world avert damage to their $multi-million computers? Each thunderstorm means about 100 surges incoming to their switching computer. How often is your town without phone service for four days after each storm? Never? They do not waste money on adjacent protectors. Instead protectors are as close as possible to what absorbs hundreds of thousands of joules - earth ground. To increase protection, a protector is located distant from electronics - up to 50 meters. Increased separation increases protection.
A surge (ie lightning) on AC electric wires far down the street is incoming to every household appliance. Are all damaged? Of course not. An outgoing path must exist. When a surge is not earthed before entering, then modems are often victims. A surge hunted for and found earth destructively via that modem. When a modem make a best (and destructive) connection to earth.
Protection from surges is so routine that damage is traceable to human mistakes. Appliance (ie modems) already have robust protection. Protection that means most so called surges are only noise. Destructive surges hunt for earth either through appliances (ie modem) or harmlessly via a 'whole house' solution. Protection inside each appliance is not overwhelmed when a proven solution exists.
Why do telco exchanges, munitions dumps, broadcasting stations, etc all suffer direct strikes without damage? In every case, protection is defined by the quality of and connection to earth ground. Which that APC and Cyberpower recommendations do not have and will not discuss.
How do 900 joules in that Cyberpower protector absorb surges that are hundreds of thousands of joules? It doesn't. It was recommended by ignoring facts and damning numbers. That protector only claims to protect from near zero (900 joule) surges. Near zero surges made completely irrelevant by existing protection inside modems.
Surge protectors that do make a connection to earth are also known as profit centers, mythical, or scams. A protector is only as effective as its earth ground. Numbers and over 100 years of well proven science explains why facilities that cannot have damage do not waste money on those near zero protectors.
Informed consumers use well proven solutions that connect low impedance (ie 'less than 3 meters') to what actually does protection. A protector is only as effective as its earth ground. Numbers demonstrate why.
One who first learned this stuff would say why some modems are damaged. How do near zero joules provide protection? They don't. Many do not even know of proven protection installed by telcos for free on every incoming telephone wire. But somehow a naive consumer knows advertising must be honest. As if 900 joules will somehow absorb a surge that is hundreds of thousands of joules.