Hi Guys,

I have a WRT54G with DD-WRT on it in a network that runs Asterisk+25 POE Aastra phones, and 48 port POE Linksys switch. There has always been problem with the router all the time. It needs reboot.

So, I am not looking into MikroTik right now. Can you tell me RouterBOARD 750 Mikrotik RouterOS v3, Level4 license which goes for $39 is the right thing for me or should I opt for something else given I need this:

-Support QoS, firewall, NAT, remote management to router.
-Support for option 66 (for asstra phone provisions), dnsmasq.
-Are all four ports on this router changeable to WAN or LAN? If so, can I bring in three different ISP to three ports and then use the last port to go to my Linksys switch? I need that for ISP failover and link aggregation!
-On router board VPN access. No pass-through VPN.

Thanks and I appreciate any feedback.

Yes.

-Support QoS, firewall, NAT, remote management to router.

QoS is called Queues and you have a lot of options there.
The firewall is based on netfilter, so it is similar in configuration to iptables from Linux.
NAT is supported of course.
Management can be done via Serial Port, SSH, Telnet, Windows Client and with other Mikrotik devices also via mac-telnet (helpful if you locked yourself out via ip firewall)

-Are all four ports on this router changeable to WAN or LAN? If so, can I bring in three different ISP to three ports and then use the last port to go to my Linksys switch? I need that for ISP failover and link aggregation!

All five ports are freely configurable as bridged, switched or routed.

-On router board VPN access.

RouterOS has support for PPTP, OpenVPN and IPSec VPNs.
IPSec is unusable for remote login though in my opinion (needs static IPs).