[Xiaomi Poco F4 (Munch) / Redmi K40S] jhonyrod:
I am very sorry to hijack a different device's forum, but XDA mods have neglected the F4 GT and we don't have a device forum of our own.

Hopefully the devices are similar enough (that being a modern Qualcomm SoC and running A12 based MIUI13) that you guys can help me solve my issue.

What happened is that I've been trying to enable voWiFi and make it stick while on airplane mode (WiFi re-enabled of course).

After a lot of back and forth with my carrier they did a kind of hard reset on my phone line. I didn't get 4/5G service for a long while, even after restarting multiple times, so I went to the test mode tool (dialing *#*#4636#*#*, which I've done several times before) and tried changing the preferred network type.

Out of desperation, after I nearly selected every other option, I selected TDSCDMA only, which is the only thing I've done differently compared to other times, and I got 4G and 5G working right after my phone did some funky radio reset (maybe a warning sign), but still no voWiFi. Decided to restart and that's when I lost the second sim slot, along with the voWiFi toggle, though it seems to connect just fine now.

Setting the preferred network type to anything else didn't solve the issue, even after several restarts the second SIM is still nowhere to be found.

After that happened the CIT menu shows both IMEI numbers as the same. (Had to censor it, but they are indeed the same).

View attachment 5717391

I've read that a factory reset might solve this, but I'd prefer another solution in the meantime. I will factory reset when an AOSP based ROM is released but I don't really want to go through the huge trouble of setting up my device again if I can avoid it.

All other suggestions involve messing with some partitions on TWRP, and while I'm unlocked, rooted and have TWRP installed I don't see why I should go that route when I was using built in tools of Android/MIUI. I'm not entirely aware to the ways that test tool works, but I can't see any where it corrupted anything besides a configuration file somewhere, certainly not messing with any other partitions' files.

I've also read that some AT commands might fix this without messing with anything, but I can't wrap my head around what I have to do (I do know where I can issue those commands, just not the commands themselves and what each does). The page I read mentions it's a temporary fix and it doesn't persist after a factory wipe, but that's kind of what I need right now.

While I don't currently own 2 sims, I was going to get one soon, and if this is a deeper issue, I'd like to know ASAP so that I can restore my phone as it came from Xiaomi and send it to warranty.

And yes, I tried inserting my current SIM in the second slot and it's not detected at all.

Is there some config file I can delete/modify that will solve this? I've already re-flashed my current ROM (as it was also suggested somewhere) and nothing happened. I haven't tried flashing through fastboot, but I don't think it's going to be different, right? Is there something related to this that fastboot would flash that a recovery zip wouldn't? Also, not going to have access to a PC where I could do this for a while (I have a Ryzen PC and it doesn't play well with my phone/fastboot).

Hope you guys can help me.