I am here to solve ALLLLLL of your problems.
FIRST! Take your PS3 and plug the USB DIRECTLY into your modem. Play for an extended period of time. Play agains't different people. If everything works fine, then we know where the problem is. BTW for a quick lesson, MB's are MEGABYTES Mb's are MEGAbits. a bit is a single 0 or 1, a byte is a string, usually 3, 5, or 8( 8 is most common) so a internet provider says they have 30Mb/s and if you download you might download at 1/8 that speed so like 3.5MB/S. ANYHOW, Now we look at your router. This is where information gets jumbled. Some have firewalls, like netgear, that you would have unlock DMZ, this means that it opens all the doors, and anything can get in. Port forwarding makes this a little safer, but DMZ is the full release. ALSO, if you have a good connection, and notice your connection drops when IDK a lot of stuff is happening, like SOMEONE JOINING THE ROOM, or THE ROUND STARTS, and it disconnects, thats because your internet has to bottleneck into your router and some routers (usually anything under $100) will squeeze too tightly and disconnect you as per you aren't moving fast enough for SCV's standards, because they only support broadband internet and your internet has fallen short.
ALL this being said, Just check your router box, look at its speed, they usually have a scale on the back that has a buncha check marks and one checkmark is for "Gaming" if you dont have a check mark in that box, you probably will disconnect a lot due to your router. 0 bars and 1 bars are sometimes becaue of routers like netgear, you fix this by port forwarding or unlocking DMZ.
That being said, YES sometimes the SCV's burp and it says 1 bar for everyone or a random disconnect, but its RARE, and usually if you are having problems fighting 1 person, and fighting other people are fine, its probably their router thats making you both disconnect...