In article , TheScullster
writes
What is considered the best sealer for cable entry points e. g. where
satellite cable goes straight through an external wall and you want to stop
water and insect ingress?

Silicone sealant. I'd goop some on the cable too before pushing/pulling it
in/through the last few inches, best practice would be to have the cable
come down to a u-bend then up & into the hole so drips on cable shed off
before reaching the sealant.
--
fred