I'm having the same or a very similar issue at home with Spectrum. I've had the same laptop (Lenovo) for about 8 months and didn't have any issues until the middle of April. I've had the same Spectrum service and hardware the whole time and the issue popped up out of the blue. One week it was fine, the next it wasn't. Like you, I've also been able to connect to other networks and everything was normal. I haven't tried the hot spot. Where our issue differs slightly is that I can actually get connected for very brief periods of time (anywhere from 1-5 min). In some cases I can even get Outlook open and send an IM (Skype) before I lose connection. Most of the time I'm not even aware I lost access until I try to send an IM, open an email or open a website. That's when everything starts lagging and eventually times out. I never actually lose connection to the VPN network; it consistently shows I'm connected even though I can't send/DL or anything. To your point, it's like I'm connected but can't send/receive packets.
Tonight I'm going to wire into the modem so that I can see if that changes anything. I've also been working with my company's help desk and they're saying there isn't much they can do because all signs point to it being a provider issue. The guy I've been working with from my company's IT sent me the link to this post and I'm going to do some more research myself, along with calling Spectrum again. The other thing my IT rep mentioned to me was something about "DS-Lite". The internal thread he sent me mentions a provider named "UPC Broadband". The issue on the provider's side was DS Lite, which needed to be removed from the account. That's something I might be able to turn off from within my network settings and I'll check there before calling Spectrum. I'll let you know if anything ends up fixing the problem, and I'll update this post with other posts I find.
