The ADI-250 works on the 2.4 Ghz and most modems/routers do as well.
Most modems are connected in the meter cupboard and will therefore be located between the two units of the ADI-250, which can interfere with the signal.
You can try to solve this as follows:
Disconnect the modem from the power supply to see if this improves the connection between the units of the ADI-250. If this is the case, try to set the modem to 5Ghz and disable 2.4Ghz. If this is not an option, you can always try moving the modem to a different location between the two units of the ADI-250.
Disconnect the units and then reconnect them. How to do this can be found in the manual on page 14 and 15.
If the above does not solve the problem and your set is still under the 2-year guarantee, you can always report it for repair via our website.
Of course, we also repair outside of warranty, the set can then be requested on the same website, however, when asking for proof of purchase on the request form, you can send a blank file or a picture of the product as an attachment.
If you have any further questions or comments, we will be happy to help and you can contact us via this link.