Confused on this cellular issue with my iPhone

Hello everyone I have a weird situation here so I got a iPhone 13 Pro Max a couple of days ago it’s carrier unlocked so I went with boost mobile I signed up put in my IMEI they sent me the eSIM I installed it and great it showed one bar of 5G. The next day I had SOS come up and nothing worked after a bit it went to 5G full bars it somewhat worked as in sometimes it worked for a few minutes that would cut out but still say 5G full bars. So I called boost we did all the basics as in airplane mode,turning the iPhone on and off,reset network settings, I’ve even factory reset the iPhone with iTunes on my pc and didn’t sign in with my personal iCloud account I made a brand new one just to see and nope still that same loop of SOS and 5G full bars so they escalated it to the manger of the IT department and they did a full service refresh and tried 3 different eSims still nothing worked so I tried apples diagnostic for Cellular and it came back as everything was good besides carrier eSIM so I thought okay I’ll go to boost and get a physical sim so I bought one and I had boost transfer my eSIM number to the physical SIM card and that did nothing actually made it worse it won’t even show bars no matter what stuck in SOS. So what I did was I tried 3 different carriers AT&T eSIM, Visible (Verizon) eSIM and T-Mobile eSIM and yet nothing at all worked so at this point it can’t be boost maybe it’s hardware but nothing seems wrong with it as it passed Apples Diagnostic with Green and in Settings and About it shows the Modem version, both IMEI numbers and shows no sim restriction. Sooo now I call apple I got there supervisor doing screen share with me on the iPhone and doing a diagnostic scan with them and they reviewed it and said nothing is wrong at all everything is fine besides that eSIM yellow… so at this point I have no idea I’ve done everything I know how to do and done it 3x over I’ve tried different carriers all the same results I’ve done physical sim I’m just so stumped here…. (Also the modem firmware is correct and up to date and both IMEI are showing I also noticed since I switched to a T-Mobile eSIM it seems to work out in the middle of the woods but in the city it’s on and off) (contacted Boost who I had before said they show nothing wrong and it was escalated to the higher up tech and they found nothing wrong either so with it not being hardware or cellular what could it be?)