Gateway Monitoring - PPPoE ipv4 interface shows offline

[planetf1]

I'm using PPPOE with dual ipv4/ipv6 stack.
Version 25.1.5_5.

I decided to enable gateway monitoring.

The ipv6 interface shows ok, but oddly ipv4 is just showing as offline (ie red status icon) Update: Specified monitor IP to a known good target (ie 1.1.1.1) which works fine. My ppp gateway is not responding to icmp.

[patient0]

Update: Specified monitor IP to a known good target (ie 1.1.1.1) which works fine. My ppp gateway is not responding to icmp.

That is often the case for PPPoE gateways, that you can't ping them.
As you did, use a public DNS or if you got DNS server from your ISP, you can also ping one of them (often a bit faster since they are 'closer').