How to alert and monitor WAN disconnects with Sonicwall

We have been using a Verizon 4G LTE router for a temporary solution until the fiber circuit is installed.
Do not have a static IP so, we are double NAT'g (less than ideal).  Using a TZ400 Sonicwall as our firewall appliance.

1)  How do we setup the Sonicwall so that we trigger an alert or monitor the WAN connection?  Verizon is saying that their service hasn't experienced any outage when we call.  The outages are momentary for the most part however, in the morning the VPN tunnels are down and we have to renegotiate them.

2)  Saw posts on setting the optimal MTU on the WAN interface of the Sonicwall based on fragmented packets.  Is this something you should always perform by pinging with the following command "ping -f -l 1500" and working your way backwards by a value of 8?

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1) configure SNMP on SonicWall (System - Administration -Advanced management - enable SNMP) and configure SNMP software (like PRTG, Cacti, SolaWinds or whatever) to inform about events you want to be informed (when some threshold is reached). I guess that SNMP is supported on your SonicWall device.
2) That kind of ping, most likely, will not help since default MTU is 1500 and traffic to google can't be encrypted. I mean it can be encrypted, but than google's server would have no idea what is coming and would drop packets. So, that kind of ping should be used to ping other VPN peers to determine MTU size that can be forwarded without fragmentation. MTU and MSS size manipulation should be set on VPN interface (not necessarily on physical links, it could be set on tunnel interface)
Check article
Resolve IP Fragmentation, MTU, MSS, and PMTUD Issues with GRE and IPSEC
1) This will help you get email alerts:

2) Yes, as long as you choose to ping a site/IP that allows ICMP traffic.

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