[Galaxy S II Android Development] downwiththebanksters:
I hope someone can help me. I can no longer get HSPA+ 3G. I realise that this might not be the exact place for an answer. I want to start here, as for my last "fix" attempt I used the CheckROM KitchenPro to flash a XXKI4 modem, so I wonder how that might impact my strategy going forward.

I decided that I had never tried any CyanagenMod ROM, so I wanted to try CM7 first, since it being gingerbread, I felt it would be easier. I flashed to a CF Root v5.0 XWLA4 kernel from the NEAK v1.4x I was running and then I did a complete backup using both Nandroid and Titanium of my CheckROM V6, and then flashed CM7. I also have, so did not make, a new EFS backup because I have a very old, but not done while the phone was "out of box" stock, EFS backup saved here in my notebook and on the phone. Before flashing to CM7 I did a full wipe data/factory reset and wiped the Dalvik too. I then flashed CM7 of the latest nightly from May 27 here .

Now here is where I can no longer be hyper precise. I tried it for a day or so and decided I preferred various Samsung and non AOSP features found here on CheckROM. I'm pretty certain that I did have at least 3G data working during the time on CM7, but can't be certain I had HSPA+. Dissatisfied with CM7 I decided to just use the CWM recovery 5.0.2.7 "restore" of my CheckROM ROM I had just made, and revert back to CheckROM6.

I simply used "restore" and all seemed working fine except for Bluetooth. (Bluetooth was originally broken when I first started with CheckROM back when ICS first became available (March?). I tried the Sammy ICS, didn't like the battery etc. and decided to try CheckROM.) I originally fixed BT by flashing Bluetooth V1 from the KitchenPro. However I tried that again after I restored yesterday and now Bluetooth won't work after again installing "Bluetooth headphone advance config v1" with Kitchen Pro. The big problem occurred tonight I noticed that I was only able to connect at only EVDO speeds ("E" in the status bar) and sometimes it would jump to "G", but I was never able to get my ususal bouncing between "H" and "H+". I checked with my colleagues Note and S2 beside my phone, with all 3 devices on the same network, and they both were able to get "H+" where mine showed only "E" or "G". I have also put my SIM in my Palm Pre and it shows "3G" and was able to achieve the speedtest.net speeds I normally get with at H+ on the S2, so I know it's not any SIM/carrier issue.

I checked my baseband version of this now running CheckROM v6 backup and saw it was XXKL4. I'm not certain if that is the modem that came with this ROM or not. I don't know if the CM7 could have installed that modem, but it remained after the restore. I decided to see if I could just flash a modem in Kitchen Pro app here in CheckROM to regain full 3G functionality. I decided to flash the XXKI4 modem as I've read it is a good modem. Doing this did not restore HSPA+ connectivity. I still have only EVDO or "G" connectivity.

My CheckROM question for here, before I go wider in my search are:

1 Should I continue to try to use the Kitchen Pro app to flash different modems to see if they restore H+ speeds?

2 Should I try to do a complete CheckROM flash over top of this restored version I'm running now fully wiping everything. I'm loath to do this as I'm basically lazy and it will mean restoring various things as Titanium isn't bulletproof. I wonder if doing this will make any difference to my modem's H+ capabilities: i.e. is the modem flashed during this process (I think it is)?

3 Should I do neither of the above and simply flash my backed up EFS file (which truly scares the crap out of me)? I have one still on the phone, plus a backup of it on my laptop.

4 Should I do a somewhat less scary thing and flash a modem in ODIN?

5 Should I do something I haven't thought of?

Again, I realise this might not be the best place to ask, but I don't know enough about what happened when I used the Kitchen Pro app to flash the KI4 modem, but for now that is where I'm sitting. Modems are scary, but very necessary things...HELP!