At most you will be able to charge smartphones and small devices with solar panels. Keeping a larger Wi-Fi router running only on solar? Very seldom.
It will not be a problem at all to power it completely on a small 100W panel.
You can even use a (right-sized) lead-acid battery without a charge controller, as they're pretty resilient, unlike lithium-based batteries. This will both store power for night and stabilize the voltage. The lifetime would be a bit shorter. You can literally just parallel your solar panel, battery, and whatever you want to power, and it has a pretty good chance of working.
Try to avoid understanding this difficulty from your own shoes, but rather from the shoes of communities very limited on what is reachable to them from a technical, financial and logistical point of view.
I know you can solve it easily. I can solve it even more easily myself.
Now see any disaster area, see any remote area. Setting up Wi-Fi is invariably never a priority for those in such situations. Even as things settle, it is still more practical to share files directly with each other.
When you see from that perspective then you are on the domain of realistic solutions rather than keyboard level on virtual forum.
The point here is to have it setup before the proverbial shit hits the fan.
Resiliency preparations are a fundamentally different ballgame to disaster recovery - you have more time and resources to prepare, your supply chains aren't broken yet, etc.
At most you will only be able to start a few Android-phone hotpspots and share files. That is the reality of it.