Thank you for the advice.
However every time I try to insert the ribbed seal it rides up the connector, it’s as if the ribbed seal is too big for the soil pipe which has a 100mm internal diameter.
I’m trying to fit a WC Swan neck pan connector and the ribbed rubber section to soil pipe keeps riding up the straight part of the connector and not sealing to the soil pipe.
I’m fitting a back to the wall toilet and I have to fit the pan connector to the toilet first and lift the toilet with...