I don't have an answer for you, but I had a similar experience with MiFi's connecting to laptops in my office. Using Windows 7 as well.
2 laptops would not connect to any MiFi with any consistency. When it did connect, it was so slow, it wasn't even worth connecting.
Other WiFi sources, those same laptops would connect just fine.
Talked to Verizon Support and he had me change the security settings on the MiFi and that seemed to help, but I didn't want to lower the security settings just for those 2 laptops..
Since the MiFi's worked on the other laptops just fine, I just didn't use those laptops when they needed to connect to a MiFi..
I've since replaced those laptops, so it fixed itself...
๐I think some computers just have a hard time with the various security setups out there.. Even changing them, didn't really 'solve' the issue, as it was still spotty connecting, but when it did connect, it was a tad faster speed, but still not usable faster..
Good luck!
Mitch
2013 F150 XLT 4x4 SuperCab Max Tow Egoboost 3.73 gears #7700 GVWR #1920 payload. 2019 Rockwood Mini Lite 2511S.