Wifi Router Crash

Ok, thanks. That's clear now. Typically, when a wireless device "crashes" the local wireless router, it would indicate either a MAC or IP address conflict. Does this same iPad have any issues connecting to other Wi-Fi networks, or just this particular one?

If it is only this one, there may be an issue with either your router's DHCP service that is not releasing IP addresses properly, or the iPad itself. If it is with any network, then the iPad would certainly be the culprit ... and a trip to your local Apple Store's Genius Bar would be in order. Alternately, you can reset your iPad to its factory configuration so that you know that there should be no conflicting apps running on it.

Ref: How to factory reset your iPhone, iPad, or iPod touch - Apple Support

What is the make & model of your Wi-Fi router? Other than updating your iPhone, what have you tried, so far yourself, to resolve this so that we don't try offering potential solutions that have not already worked for you?

If the WiFi Router can be crashed by a potentially malformed packet, or a duplicate IP/Mac address, I’d strongly recommend that the Router is replaced sooner rather than later.

In such circumstances, the Router is fundamentally unsafe (from the perspective of security) to be connected to any internet facing network.

Ok, so you have your iPad updated to iPadOS 15.5 ... correct? Have you tried updating it to 15.6? ... or is this what is crashing the router?

Also, by "crashing," do you mean that you router goes off-line so that none of your wireless devices can access it?

Maybe not enough coffee yet, but I just want to make sure I understand. When you say that your iPad is crashing the router, are you saying that not only this iPad cannot access the router's wireless network/Internet access ... AND, this is true for all of your other wireless devices when this crash occurs?