Or build a PfSense Firewall-Router, which is free & open source. All you need is a basic PC (ideally with Intel I5 or better & 2GB or 4GB ram).
I run PfSense behind both my VM at BT modems, with PF load balancing the connections. For remote access I use OpenVPN server for inbound. Clients connect via whichever WAN responds first. It will also support IP-Sec if you want. Both modes also support site-to-site VPN where you want the connection always active.