Nat Typ 3 on Ps4

Hello @ai.enma0808  
What kind of internet product do you have?
My guess would be an “NetCube” or nowadays only called “Cube” mobile internet plan for home aka broadband replacement.
 
For the PS4 problem I would guess you do not have a public IP address. If you have a mobile internet plan for home, you can get one for free through “Mein A1” (my A1) or A1s’ customer service.
More information on how you can get a public IP address for mobile internet plans through “Mein A1” (German): https://www.a1community.net/news-431/oeffentliche-ip-fuer-mobiles-internet-ab-sofort-im-mein-a1-bereich-bestellbar-a1-mobile-dynamic-ip-254181
 
For the bandwidth issue it would also be helpful to know what kind of product you have from A1. As I said it sounds like you have a mobile internet plan for home. For these kind of internet products, the position of the router is especially important so that it can receive a signal from the closest cell tower. The better the signal the higher the data speeds can be. It also depends on which router you have because modern routers can achieve higher data speeds if the network in your area can deliver up to 300 or 500 Mbit/s (Mbps) over 4G/LTE.
If it is a possibility you could switch to A1 broadband which should provide a more consistent experience
A1 cell coverage map (German): https://www.a1.net/hilfe-support/netzabdeckung/frontend/main.html
A1 broadband (“Internet für zuhause”) availability check (German): https://www.a1.net/verfuegbarkeit

A note on the A1 broadband availability check:
It does not only show A1 broadband over landline or fiber (“Festnetz-Technologie”) but also over hybrid technology (“Hybrid-Technologie”).
Hybrid technology combines landline and 4G/LTE into one internet connection.

regards NerdTech