Be a cheapskate, use lower rating ELCB.
Spend more on your ground, original grounding point provided by developer are not deep enough.

Guess you make it wrong already.
For your friend case, it is coming through the phone line. Happen to me twice. I'm using lower rating ELCB.

Is it? So signal transfer using optical don't have current

Fiber optic or copper, it is just used to transfer data. And you need current to transfer data. You no need to have much, just extra 10-20A surge are more than enough to fry your appliance.
And if that extra surge of current are really going through electric pole, the damage done won't be just unifi equipment only. You will need to change 50% of the house appliances.

Use wireless modem and don't use network cable.
Now Streamyx TM improve the system already, their junction box now comes with auto reset ELCB(think unifi don't have yet), whenever there's thunder storm in my area, I sure can't go online. And once over, I can use it back.

Still, it need to do conversion, right?

But why just the phone related stuffs only fried?
This is something we really look in to it.
As said, if it is from the main electric cable, the damage will be more, but if the damage like isolated like this, I highly doubt it.
If we don't make it clear then same sheet will happen again.
Till today, I fried 4 motherboards, 4 display cards, 4 power supply, 3 modems and 1 cordless phone. All of them are covered under warranty, so FOC, MBs only the network port fried which affecting display card and power supply.
An electrician when have a first glance check already can tell from where the frying job starts.

Yup, fiber optic does not transmit current during digital stage.
But it will be interesting to know the actual cause on this.
Autogate board need to check the operating voltage, if low voltage type, sure it will blow fast.
And if the lightning really strike the pole, the TNB digital meter will be first to go. Happen to my house once which ended up I got 75% of discount for my bill.

Yup, but TNB now are slowly phasing out analog meters.
Even the reading blown, once reset the main fuse, I still have power