No WiFi in Debian after suspending or closing the lid

I know that this question is posted a few times already, but I tried many of the solutions there and they didn't work. If I start my Laptop (restart or fresh boot after being turned off) the WiFi works most of the time and I can connect to it without a problem. *Not always though* If I'm connected and close the lid or press the power button so that the laptop goes into suspend mode, after I open it up again, I can't connect to the internet. The available networks are shown, but all of them only have a 10% strength and nothing happens when I try to connect to them. If I deactivate and activate WiFi again (either by the switch in network-manager or by the F-Key on the keyboard), it shows WiFi as "not connected". I tried to restart network-manager after the suspension, but that didn't fix the problem. I know that this is not a lot of debugging information, but I'm not knowledgeable enough of Linux to be able to give you a more relevant one. But I'm happy to provide it, if you tell me what exactly. EDIT: After thinking about the problem a little bit more I also remembered the following: If I let the Laptop suspend by going idle and waiting for the 5 minutes it requires, I sometimes have WiFi after booting up again. It also happened recently, that I was playing in offline mode (because I had no WiFi) and after quite some time I could connect to the Internet again (I think about an hour, but I'm not exactly sure). I have seen this phenomenon very rarely and it only happened on a few occasions.