4g not working well...slow..how can i fix it

• R = roaming as you found out
• E = Edge, or 2g...its really slow but works in a pinch
• 3G = 3g...still slow but better than Edge
• H = HSPA, its a form of 3G just a lot faster...this was considered 4g before true 4g
• H+ = HSPA+, same as above just faster
• LTE = 4g LTE. its the fastest of the bunch.

R is for roaming. Maybe your network doesn't allow data on roaming?

Sounds like you are using a cellular modem. Internet through the cell phone network is usually always going to be slow, nothing can change that other than making sure you have a device that supports 4g and you have 4g signal. Anything else is going to be slow and the lower the signal the slower it will be.

depends on network ie 3g or 4g sometimes the network goes to sleep on i phones when unavailable try wifi from a hotspot on icloud app fast connect or at home on router just log off and turn the 3/4g on or off if your using wifi turn 3/4g off ok

I suppose that what you mean is that you can access your wifi networks but not your service provider's network.

If that's what you mean, check the user's manual CLICK HERE page 122.

you must chek your 4 g setting of your phone with follo the link or pic How to Fix iPhone stuck on EDGE 2G Problem

I had the same issue. Its hardware related due to no good contact between the phone and your tiny speaker.
To fix it no too hard.
1) Open up your Samsung infuse case directions here video http://www.youtube.com/watch?v=ewdyo2fkJj8
or pictures http://androidforums.com/samsung-infuse-4g/532693-how-fix-samsung-infuse-4g-screen.html
2) The speaker is located bottom left corner (two etched holes for sound)
3) With cover off locate 2 brass/bronze tabs that connect the phone to the speaker.
4) Slightly lift these tabs make sure not to far to brake off (1 mm)
5) Put back the cover and phone speaker should work fine
I hope this helps.

Did you tried press the power button while holding the Home Button pressied ?

Some cards are available that work at faster speeds and I would definatly try reformating card from within the camera menu