lightning storm

I’m pretty sure he meant more than one earth connection to the electrical grounding system of the house. (From mother earth to the inside of the house and back out of the house to mother earth.)

Nope. 

Lightning strikes from coax or network connections aren’t necessarily from ground to ground.  They seek ground potential, but they are not necessarily carried in by the ground conductors. 

What the tech was referring to is that lightning potential seeks a path to ground, and will find the lowest insulated point to go through.  

This is a reason why I specifically do NOT recommend grounding Ethernet "surge protectors."  Best to deny a surge a path via isolators than to allow a low voltage current path which may also convert common mode to differential and enable the passing of a surge downstream. 

In the case of an outside surge coming in from other than the power lines, the series mode protectors have the edge as instead of encouraging the surge path they deny it, but only on the hot wire I believe.  

@hifidream  - I'm curious.  What, if any, coax protection did you have at the time?  We had a significant near by strike here when I moved (2021 I think) that took out the cable provider's equipment and every single modem in my small subdivision.  I used an outdoor gas discharge protector.  While I did lose the modem, the Wifi router it was attached to and all the gear attached to it directly was not affected. 

The Internet is filled with stories about lightning coming in via the cable modem and taking out entire HT systems via burned out Ethernet ports. 

Most Internet users rely 100% on Wifi, but for those of us who use it professionally or just don’t like to have Wifi problems we wire all our big gear up.  Our work computer, TV, music streamer, etc. and so I take a paranoid approach.   Using Ethernet is great for reliability but also leaves us more exposed to incoming surges.  

I use an external coaxial surge protector with gas discharge tube.   Internally I air gap the modem and router with fiber/Ethernet converters and at the end of long runs I use Ethernet isolators (not surge protectors) which are tested to UL 60-601

Even when lightning does not directly strike a power line the magnetic pulse is picked up by every cable nearby, from high tension lines to your house wiring, antenna cables and Internet provider's wiring.  

We don’t always know when a surge will come down the line so having a good surge protector is essential IMHO, but even then I would absolutely recommend unplugging when you know a big storm is coming through.  Sometimes I even turn off my HVAC and range as well, despite having a whole house surge protector.