For those who don't have Festools, the dust port on the OF-1010 router
is oval and doesn't fit the hoses very well. The round 27mm hose end
has to be forced around the oval port.

For those who do, I found this adapter. It works really well.

https://www.ebay.com/itm/265073864218?_trkparms=aid%3D1110002%26algo%3DSPLI CE.SOI%26ao%3D1%26asc%3D20201210111451%26meid%3De7 ba0f708bbc4ac3ac8600bf2e62e282%26pid%3D101196%26rk %3D5%26rkt%3D12%26mehot%3Dpf%26sd%3D264823814169%2 6itm%3D265073864218%26pmt%3D1%26noa%3D0%26pg%3D204 7675%26algv%3DPromotedSellersOtherItemsV2WithMLRv3 %26brand%3DFestool&_trksid=p2047675.c101196.m2219

I'm surprised Festool doesn't sell it. The price is about right.