The issue you're describing happens when the dvr is connecting via Comcast internet
I understand... That's what's weird. I am 100 percent sure I do not have Comcast internet only tv at this location. I use tmobile home Internet. If I'm putting junk in the login credentials your would it even know what account and whether auto auth is in or off? It's not a real account in that case. That's why it seems like it's not even getting to login... Cuz would it not says auth failed instead?
I will check with Xfinity and see if there are multiple accounts for some reason. But the login works at nbc.com/live so i think I've got the right credentials and I verified auto auth is off for those credentials.
Thanks so much for your help btw.
Comcast states that there is no way to stream other than from the xfinity app...However, I don't think I believe that - most likely just someone who is trained (or not trained well enough lol)
They also confirmed that my internet and tv are under the same account.
That is partially true that using their app you can stream all their Channels ... TVE is just another vehicle to watch certain Channels and you need to use their credentials.
Yeah, that's what I pretty much know to be true also...just was wondering if maybe somehow they found a way to reject any connections not coming from their app. Because I don't see any kind of authentication failure when i use jibberish for credentials...it just says "not in subscription" but how could username "jkjsdf" even have any subscription.
Something must be wrong with your setup I am om Comcast/XFINITY and my TVE is working ... did you submit the logs or trouble shoot in the web page ? See troubleshooting below.
I've run the troubleshooting a couple times. Looks good...I don't really care about remote access.
I will upload logs next.
can't figure out how to upload the full log file...but here is most of the last attempt to add xfinity...
Thanks! Done 
Maybe your VPN is causing problems
I tried it with vpn disconnected and connected. Neither worked. 
I tried logging in with DirecTV login and it worked. But then Comcast still didn't work. So it feels like it must be something with them.
Yes. The problem is that when the DVR clicks this in a Chrome incognito window, no login form is shown for it to be able to enter the user/pass. It logs in automatically to some account which doesn't have a cable tv subscription
I see. I wonder if maybe there is a saved password or browser session somewhere allowing it to do that.
There's no saved anything in chrome incognito
Ok, I think we figured it out. Your last message made me think a bit, like if it is incognito, why is it auto logging in with different credentials...Everytime the window opened to add the source, it would put a username and password in there automatically. EVEN after I deleted all cache, cookies, and passwords from my browser. So on a hunch, I just uninstalled the DVR server, reinstalled and loaded a backup from before all this, and now it works to add xfinity.
When I get that error, usually step 9 (which clears the chromedata folder) fixes it for me.
I do this before rescanning individual channels and before remove/re-add source.