[Scoundreller]

You can also find barrel splitters. I use one so that my 12V router and 12V modem both run off 1 wall-wart.

Look to be common for security cameras.

Like so: https://www.ebay.ca/itm/113713154440

[voltagex_]

Did you do any testing to figure out how many amps you're drawing from the single wall wart? Although, modem/routers in normal usage are pretty low draw.