I was told previously that the v1 and v2 hardware is incapable of meeting the Apple security requirements for HomeKit. This is not a MFI chip issue.
So it would sound like the only option would be a return or for Tado to offer a discount against a v3 model. Tado have offered such discounts for existing customers before so lets see what they come back with.
Unfortunately, it is not possible to bring HomeKit support to our Smart AC Control V1/V2 hardware version.
To be compatible with HomeKit, the Wi-Fi chip inside the Smart AC Control device has to support IPv6. However, the V1 and V2 versions of the Smart AC Control only support IPv4. This means that if you would like to control your AC using HomeKit, you’ll need to upgrade to the Smart AC Control V3+ hardware.
You can find detailed information on the differences between the tado° Smart AC Control versions in this Help Center article: https://support.tado.com/hc/en-gb/articles/360028629331
If you would like to upgrade your tado° App to the new V3+ version, there is a special offer to do so for free which you can find in the app. With this upgrade, you and all the residents in your home can benefit from lifetime access to the Auto-Assist Skill: https://support.tado.com/hc/en-gb/articles/360015213512
After the upgrade, you can add the new Smart AC Control V3+ hardware to your account at any time without losing these features.
However, this V3+ app upgrade does not add HomeKit compatibility to your V1/V2 Smart AC Control devices.
Please note that this free app upgrade is a limited, temporary offer to our V1 / V2 Smart AC Control customers, the standard price is €/£ 19.99.