Recommendation/Advice on Small Office Set Up

I am looking for some advice into setting up networking for a new space. Originally our business (2 employees) was very small and piggy backed on our old landlord's internet, so we never set up our own. We just moved in last week, and is temporarily running everything through a Netgear AC 1900, Ideally, I wanted to do Modem--->Router-->Switch, but we got no ports :(

Our new space is on the 2nd floor of a 5 floor office building, the internet connection is 500 Mbps down/25 mbps up. We now have 6 staff. At this new location, we also switched our phone service to Ring Central (VOIP). We got four medium sized offices, and one conference room. The hardwares in our office are - 3 desktop computers, 3 laptops, one smart TV for conference rooms, 6-7 cell phones, and two printers.

Unfortunately, none of the rooms have ethernet ports. The Modem is set up in my office right now, and we have the router in this room as well. We only had this set up for two days, but generally speaking we haven't had much problem with our staff running everything on wifi.

The only issue is our quality of our Voip. My phone is connect by ethernet to the Netgear router, but everyone else uses the Ring Central App on their cell phones. Speed tests shows that the Phones are getting pretty good speeds, but for whatever reason everyone gets occasional dropped calls for a few seconds.

Should I invest in new wiring in our floor so everyone gets ethernet port in their office and set up my office like a server room? Can I get by with just using powerline for the Voip phones (we have the physical cisco phones, just couldn't use them since we don't have ethernet ports)?

Thanks! Very appreciative of any response.