The two R&B icons hopped back on the 'Gram Monday night to pick up where they left off over the weekend -- which went down in a fireball in what proved to be a huge fail. Welp, fortunately, running it back turned out to be a bit more successful (the guys were actually able to play some music and hear each other this time) but eventually ... it came to a halt.

So here's the gist ... Teddy and Face were on the same page at first, and did exactly what artists are supposed to do for these Live battles -- namely, play their biggest hits back and forth, and let the audience tuning in to decide who takes the round. That went on for a solid hour -- IG Live only lets you broadcast for that long -- before the feed finally went dead.

The guys came back on for another session, but for one reason or another ... Teddy's feed cut out completely not too long after they booted back up -- which caused confusion. Babyface -- at first, not entirely sure why Teddy had hopped out -- eventually stopped down and logged off himself to go and see if he could get on Teddy's IG Live sesh.

At this point, it turned into a game of Who's On First -- Teddy had, indeed, started his own IG Live sesh, but was back with a full musical set-up with live instruments. As he was waiting for Face to join the session, he started playing music to kill time, and was going IN doing it. Sadly, he didn't realize Babyface was at the door asking to be let in -- Teddy was that distracted -- and finally, his team got through to him. Everyone in the comments was trying to tell Teddy too, BTW.

This is where the "breaking the Internet" part happened ... Teddy was not able to let Baby back into the chat, try as he did. People chalked it up to him being an elder and unable to figure out the tech, but that's not the case ... it was Instagram's fault. Their network was jacked up because of how many people -- several hundreds of thousands -- watching.

It got so bad, IG finally had to say, "We love how much you're all enjoying the #TeddyRileyvBabyface Live on Instagram! We're experiencing some technical difficulties on mobile apps but we're working on it. In the meantime, live is available on desktop!"