UPDATE i think i found the problem, dhcp server overwrote my default gw pointing to old gateway on different IP 
hi
I’m a new user to RouterOS/Routerboard and purchase a 2011UAS-2HnD. I have it connected to a comcast CPE modem, using DHCP to get a WAN IP. initially I was on 5.21 and could never get srcnat to work at all. the router is able to see the internet fine and I even upgraded it 5.24.
I reset the settings by shorting the reset pad on the board while powering up.
I used the quick setting (home AP - new in 5.24?). i can see in the DHCP client window that it received the WAN IP and setup the default route to the WAN gateway. briefly I could ping the WAN IP, remote gateway and internet, looked around a bit in all the options and then tried to browse the internet, the WAN connection is gone again. I cannot ping the WAN IP or further from the LAN side, everything looks fine as far as I can tell, just cannot get this to work 
Attaching some screenshots of relevant configuration.