[[EDIT: I just had to restart after I installed the drivers, it works now. 
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I bought a TL-WN725N (TP-LINK) USB WiFi adapter. I had a driver from my previous adapter (which broke) installed, and it worked. Except for one thing: wherever I went, the connection was extremely weak. One turn and I could be disconnected. I could be standing right next to the router and hardly get a signal. Once I installed the provided drivers, it doesn’t work at all. It may be a compatibility issue; my router is 300 Mbps, while the adapter is 150 Mbps. Please help! Also, if the adapter and router aren’t compatible, does Ubuntu MATE 15.10 support PCMCIA cards? I found a PCMCIA wireless card on eBay that is the same brand and speed as our router.