This was already said, but I'll just say it too.

From what I have been told by authoritative sources, it's almost entirely about the medians. Your application is judged on 3 things: LSAT median, GPA median, and your life story. You fall into one of three categories: 'high/high' (above both medians), 'high/low' (above one, below the other), and 'low/low' (below both). 'Close' doesn't count for much: if the median is a 168 and you come in with a 167... then you're categorically a 'low', unfortunately. And it's pretty much the categories that count. If the school is admitting a class of 100 students, then the top 50 in each median category are there to establish (and protect) the sacred median, since that defines the school's rankings. The bottom fifty would be there because they're protecting the other median, or they have something special to add to the class (work experience in a field that would make you a unicorn in law, life experience that would look good when highlighted in the alumni magazine, Dad's a senator, they just like the cut of your jib, whatever). Basically, the admissions officers try to balance who they let in to produce what they consider a great class cohort while first and foremost protecting the medians; candidates from all three groups are admitted, but if you're a 'low/low' you need to be really interesting in other ways. High/high status is likely a green light unless your story disqualifies you in some way, high/low status and a strong story has a very good shot.

With that said, I don't think you need to worry so much right now. With your GPA, you can't be a high/high (neither can I, and not for any cool reasons like being an NCAA athlete!), but you can still be a high/low by just beating any school's median by a single point. 157 is not nothing! It's a solid diagnostic score that would already beat median at a lot of schools, and you still have plenty of time to improve it. I don't see any reason to suppose you won't. And remember (except for scholarship consideration), all you have to be is a point above that school's median to fit into that high/low status and become a real candidate for them. I think it's way too early to panic.

If they claim it's a "known issue" then that implies that SOMETHING is broken on their end. Whether that breakdown affects EVERYONE or just you (or a small subset of people that you happened to end up in because of who knows what software/hardware/network stuff) is unknown. I think I'd keep troubleshooting; if it's not affecting everyone then maybe you can find a configuration that would work for to get you connected too.

Some stuff I'd investigate:

I'd look into what your network is like between the Macbook and the internet. If the on-the-computer stuff isn't helping, the problem may lie in the network itself. Try connecting from another network (if you've been doing it at home then try instead to connect at work, or the library, or at school, or a friend's house, or all of them!) That will give you some data to work with (if it doesn't work anywhere, it's either on their side or it's your computer. If it works on one of them, it's NOT their side and it's not your computer. Make sure to chart it out with lawgic and consider contrapositives, since this is the LSAT). Any network level firewalls, proxies, or DNS settings may be contributing to the issue. Depending on what network you're on, fixing some of those may not be in your control and you'd have to find someplace else to connect from.

If swapping networks a time or do doesn't show any change in the behavior, then the issue presumably lies in the computer (or their "known issue" is really big). This means the same sorts of test: try a friend's computer and see if you get a different result. If your trials indicate that it appears to definitely be your computer, consider creating a new login on the MacBook (so that no weird preference or past Chrome installation junk might be a problem) or even go nuclear by completely resetting the Macbook to like-new condition.

Good luck. I'm actually considering buying a clean mac mini for the test, just because I'm enough of a nerd that I'm pretty sure all the security stuff I've played around with on my computer/network will DEFINITELY put me in the same spot you're at. At least your computer is portable, so you can easily experiment. If you can find a friend's computer to try on, that would be a huge diagnostic as well.

I agree. The point of the diagnostic is to establish a baseline of your raw, initial capability so that you can know where to focus your training. If it’s not going to discourage you or anything like that, seems best to do it immediately.