Cell Phone Calls Using WiFi Don't Go Through (Intermittently)

Thanks for the tip I'll check it out.

I have two of those exact routers.  One here in VA on Cox and the other in Canada on Rogers.  I have never had any issues with WiFi Calling on either of them.  What are your speeds for your ISP?  Cable shares a lot of bandwidth with neighbors, so that can significantly impact your speeds and meeting that WiFi Calling threashhold during peak hours or when your service is being use heavily.

At the moment, the speed is 438/24. I've never seen it less than 400/ 20. I did have the ISP come out to figure out if the problem was on their end, and I've got a really good line with no noise. Also, if it was over usage of the cable circuit I would expect it to occur at specific times of the day, I can replicate this issue 24/7.  Since you're also running Asus Routers I will tell you that I did turn on / off the mesh to see if that was an issue but there was no change.

The upstream there is the key.  Anything needs to send to receive.  If you are placing a WiFi call, you are using about half of your upload speed just for people to hear you.  If those speeds get too low, the person on the other end can't hear you or the call being placed can't be connected. 

I don't use mine in mesh, even with multiple.routers.  I have an old RT-AC68W just for all of my Amazon Echo devices and my Brother laser printer.  I primarily use my RT-AX86U's for PC's, laptops, and phones on 5GHz and 6GHz.

The issue is both ways.  Calls coming in get diverted to VM and never ring through.  Inbound texts never go through.

If I reboot the phone it will work for about 10 minutes, then goes back to intermittent functionality.

What device are you using?  Have you tried a WiFi and Bluetooth reset?

Phone is a Samsung s23 Plus. Every device in the chain has been taken back to factory reset and reconfigured from scratch.  

Android has introduced some issues with WiFi Calling that Samsung is aware of.  It doesn't just affect T-Mobile's WiFi Calling as it affects other Implementations of WiFi Calling for other carriers as well. 

As an S23 Ultra owner from 11 days before the official launch.  I have participated in the official Android 14 beta all of the way through and was one of the many that reported the issue that made it into the final build.  Hopefully this will be fixed in a future update.  

I could accept that as the reason, but I wish Samsung had told me that at some point during this process. They replaced the phone for me when I started running into these problems and was working my way through the various chains of people who could help me troubleshoot what was going on.