I am having the same reception issues and I tried the fixes with the same negative result. I previously had a Samsung with Verizon with no issue I now Have a Samsung S8 and reception is so poor it makes my phone basically unusable for phone calls at home.
For some reason I only show 1 bar of signal strength at my home in San Francisco, CA. Even as I go about the greater Bay Area I typically only have 1-2 bars of signal strength. When I toggle airplane mode on/off I get up to full signal strength for a few minutes but then it dips back down to about 1 bar of signal strength. What is going on hear? Very recently switched to Xfinity Mobile and I am so far very unhappy. I live in the middle of a huge metropolitian area, signal strength should be strong. Also the latency issue is a huge annoyance. Is this just the way it's going to be with Xfinity Mobile or is there a fix?
Also in San Francisco (outer sunset). iPhone 5C (originally on Verizon but now unlocked), iOS 10.x (not iOS 11.x so no WIFI Call feature for workaround) Observe the following interesting behavior
1. Did all the improvement attempts : reboot, airplane mode on/off, force PRL update (power off, SIM out, wait few min, SIM in, power on) No difference.
2. Accessed the Field Test Menu (call *3001#12345#* on iPhone) and can see signal dB.
3. At sleepy residential outer sunset neighborhood (6 block from ocean), observe -100+dB so clearly pretty bad signal. Also shows physical tower number and tower ID. Unfortunately couldn't find any websites (cellmapper.net) or apps (open signal) that shows match ID so no idea where the cell tower is. Open signal app figured out carrier is XFINITY MOBILE and pull up all nearby XM towers in its database. Unfortunately, no match to ID/number from Field Test Menu.
4. At commerical inner sunset (19th and Taravel), phone shows -100+dB but when call is connected, instantly improves to -75dB. When call terminates, goes back to -100+dB. This pattern doesn't occur in case #3.
5. Brought the phone to Seattle suburb and see -110dB. But as soon as phone call connection is made, it gets to -80dB and have no problems. This is similar behavior to #4.
Its hard to believe Verizon would be this bad in outer sunset (probably biggest patch of flat terrain in SF). Xfinity Mobile's MVNO agreement with Verizon must get something less than the full Verizon network? Also why do signal go from -100dB to -75dB during the call?
My story and how my decision to get new service with Xfinity Mobile has been a nightmare. About 5 months I bought a Samsung S8 Plus, immediately after receiving and activating, I noticed my signal bars were at 1. Hardly able to walk inside my house with any signal on the phone, I immediately contacted support and was informed this may an activation issue and they had to resend some codes to the phone. Needless to say, it did not work and the ticket was created to a tier 2 team whom never called me to discuss.
A few days passed and started to notice how the signal was not only weak at home but calls dropping while I drove around town, mind you, I also live in a metropolitan area where signals should be strong but yet again, not my case. I found myself calling Xfinity again, this time I was able to speak to a tier 2 team member who again assured me that updated codes along with the removal/insertion of the sim card would fix the issues. After multiple calls and ticket escalations and factory resets on the phone, I was given the option to complete a warranty exchange.
Here I am 5 months later still having poor signal inside of my home with the replacement phone and I am having to deal with a reburbished phone although I paid for a brand new phone and Xfinity Mobile claiming I am responsible for the phone price stating there is some kind of display burn which is not something I ever had or complained about at all in any of my calls to the technical support team. Now yesterday while again I called Xfinity regarding the low signal on the replacement phone, I was informed there will be a charge on my account for the full price of the other phone that I have already paid. After an hour on hold I was told that due to the extensive notes on the account they will make a notation to not charge me for the phone, but now I am finding myself paranoid that my checking account will be swiped for $800.
If this is not the worst service from a phone company, I do not know what is. All I know I am watching my checking account every hour on the hour like a hawk making sure that if the funds are taken out, Xfinity Mobile will speaking directly with my attorney.