Unable pairing for Microsoft universal foldable keyboard on Ipad 9.7 IOS11 bluetooth

Dear Sir/Madam,

I am using microsoft universal foldable keyboard for quite some times but after recent upgrade to new iphone 7 and Ipad 9.7 2018 for IOS11 that it shows the error as follows:- "Pairing took too long. Make sure "universalfoldablekb" is turned on, in range and ready to pair". Please advice any solution on this. Thanks.