Hi, and welcome to this Apple (user-to-user) Community!
Re: "Rexton hearing aids with ios26 " my Rexton hearing aids disconnect frequently"
Hearing-aids will often need a firmware update (and / or an app update) to remain compatible with the latest software. There are often details about firmware updates in the hearing-aid manual, or the hearing-aid manufacturer's support website, or from your hearing professional.
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Re: I have to restart phone and/or take hearing aids in and out of charger.
You can also try turning Bluetooth off, wait a few seconds, and turn bluetooth back on.
If your hearing-aids are listed in Apple Support's (Mfi) List below they can use the iPhone's accessibility software,
else they may need to rely on Bluetooth for connection, and an app for control.
List of Made for iPhone hearing devices - Apple Support

If your hearing-aid model is listed above:
Check the Settings to make sure your hearing aids are listed correctly, and are available there, for connection.
Check: Settings > Accessibility > Hearing Devices controls.
More info.. if needed: Use Made for iPhone hearing devices - Apple Support
Eg: says:
"Make sure that your hearing device is updated with the latest firmware from the manufacturer.
If it has its own app, that app can probably find and install firmware updates."
(Much more info. in above linkd article,)
All the best :-)