Netgear GS418TPP restarting when connecting with Fritzbox router

We have an existing situation with Netgear switch GS108PE.
Since it has become too small, we have purchased a new one GS418TPP.
All network connections work on the new switch, but if we also connect the internet router, the swicht will restart after a few seconds.

The switch keeps repeating this.

Network is connected to the internet via fritzbox router (fiber optic).
Router is set as DHCP server for the network.
No further details in the network, standard PCs

I hope someone can help me with this,

greetings avdbrink