Wi-Fi Assist keeps disconnecting on my iPhone 15 Pro

My iPhone 15 Pro (iOS 26.2.1) consistently drops out of cellular WiFi assist. This is not a new condition but has been happening regularly over the past year +. It's my personal phone not associated with any company. Normal state I can take/make calls, text etc. over my home WiFi network but without warning it will stop functioning. Generally I discover the issue when I try to make a call and I get an error message informing me "no cell network is available" and I should turn on WiFi assist (it IS on). In settings if I toggle off and on, that does not remedy the issue. I must toggle WiFi assist off, restart my iPhone, toggle WiFi assist back on and . . . I immediately start receiving missed texts and voicemails. Sometimes the phone will work for several days without requiring me to perform a reset, other times I have had to reset it multiple times in the same day. There doesn't seem to be a pattern.

[Re-Titled by Moderator]

Original Title: WiFi Assist Issue