I did the same when I joined my last job. They were running everything off two BT business hubs. I've put both of them into a brain-dead modem mode, with one as

I did the same when I joined my last job. They were running everything off two BT business hubs. I've put both of them into a brain-dead modem mode, with one as a failover WAN, bought a Mikrotik RB2011UIAS-RM (which has been wonderful, 100% uptime), replaced the 10/100 switches with gigabit equipment and installed a set of four Ubiquiti WiFi access points around the building. We've got a nice guest wireless network for our clients with token based auth and a really reliable and consistent office network. I recently bought a Mikrotik HAPlite for home which has also been great, I can VPN in and check my security cams without any horrifying cloud service getting a livestream of my home.