Bad internet despite fiber optics?

About 2 weeks ago the technician came to set the fiber optic line for me and everything went well, except on the Ps4, where the router is actually connected to the Ps4 with a LAN cable. I ordered a 125k line but the connection always fluctuates up and down during the internet test on the ps4. Sometimes it is 70 then 100 then again 60 and the next time 90, which means the line is not constant even though it is connected to a LAN, but mostly it is more in the 60-80 range which should simply not be. I would like to use my entire internet but do not know where the problem is, so I need your help or help from someone who is somewhat familiar with it. I've tried almost everything. Unlock the ps4 ports on the router, restart the router and even called the ps4 support, but they only said that it is due to the internet and I should contact the provider, but it can't be due to the internet because I'm all 125Mbit / s Get cell phone through WLAN, CONSTANTLY, but then only get 80 on average with the LAN cable on the ps4 and the ping in playing 50-60 is just too much. So does anyone know what I can do?

You should be aware that you can get up to 125k if you have booked a 125k line. But that doesn't mean that 125k will also reach you.

Does your house installation manage the higher speeds at all? The fastest internet is of no use to you if you have a Cat 4 cable behind it.

You have fiber. You have Lan KABEL. You did everything you can do. Your internet company is messing around. Go there.

Yes, but it all comes down to the cell phone even though it only works with Wi-Fi, but then only getting 80 with a direct cable to the router is weird or not?

As already described in the text, I get perfectly every 125 Mbit / s on my cell phone even though it only runs through Wi-Fi.

Yes, and as you wrote, your PS is connected with a cable.

Genoa, and therefore it should run better with cables or not? With a LAN connection everything should work better, but it doesn't.

The fastest internet is of no use to you if you have a Cat 4 cable behind it.

As I said, I'm not very familiar with something like this and do not know what cat 4 is, but where can I check whether my cable is a cat 4 or not?

Then I pull something out. With every cable connection you have to deal with data loss. In short, the Cat class describes the ability to transport data without loss (the higher the number, the better the cable). - The same applies accordingly to plugs and sockets.

A Cat 4 cable is an outdated standard (at least Cat 6a parts are currently installed in new installations).

You can usually find this information on the cable itself - except often for cables that were supplied somewhere.

The solution to your problem would be to try a new connection cable between the router and Playstation.

Have looked and have CAT 5e

Is the Playstation directly connected to this cable on the router, or does it run through a wall socket? If it's connected directly, just try another cable. Otherwise, it can of course also be due to the cable in the wall.

It is directly connected to the router and I've already tried the cable that came with the router… Same problem.

What comes to mind, use a different socket on the router. If that doesn't work, I can't think of an "uncomplicated" solution anymore.