Changed modem, internet on all OK but no network connect to 2 mac's

Today our country internet / phone service joined the 21st century & we now have 25mbs internet service. That's the good news. The bad, sort of, is to do this it was necessary to change the modem & now the internet on all computers is working but no network connection between all computers (PC & 2 mac computers). Not sure how to fix this. It would seem simple but (?).

Need some help, please.

We had changed from wireless to wired for internet as wireless was too slow. This changed the network connections as it was looking for wireless. Had to go to provider's LAN connection to update this computer to wired & all is working now.