When in doubt, you can usually compare the
Google Trends. In this case, the trends are very close.
In most similar cases of imported words, I tend to think the longer form is more technically correct (ルーター), but in common usage they are interchangeable. The longer form may be closer to the original English pronunciation, but the shorter form more naturally fits into Japanese phonetics. This is just my opinion, I don't have any sources of linguistic research to back it up.
As for type-in traffic, maybe the shorter one would be better, but I can't say for sure.
If it's a good term, I would take both or whichever is available.