I'm back.
Worked the first time (Linksys to Linksys).
Settings were basic. Same on both sides...
Local: "subnet" 192.168.0.0
Remote: "subnet" 192.168.1.0
(flipped it for the other Linksys)
mask was 255.255.255.0 for both
IP Addr. (I have statics on both sides)
Des (faster)
SHA (faster)
Auto (IKE)
PFS (stands for Perfect Forward Secrecy)
Key Lifetime: 3600
clicked more...
Phase 1: Main/DES/SHA/768/28800
chose 28800 to make Phase 1 last "all day" (8 hours)
Phase 2: 768/3600
Anti-replay (not relay, as some have suggested)
Has to do with an attacker re-using one of the
encryption keys
Keep-alive
After "Apply" I *did* click "Connect", but only on one side (as it should be). All worked at this point.
Block WAN was enabled (the default) and had no effect on my VPN.
Other notes:
Verizon? Verizon is a melding of several smaller (though still large) networks. Very possible that one part of the country is blocking when another part of the country is not. They haven't merged completely, yet.
Blocking port 80? Yes, several ISP's block port 80... *inbound*! They don't want people from the outside requesting web pages from your machine. That does *not* block port 80 outbound, thus allowing you to request web pages from the Internet.
50? That is *IP protocol 50* (aka Encapsulating Security Payload (ESP) which is the encryption), not TCP (IP protocol 6) or UDP (IP protocol 17) port 50. It's a completely different animal from IKE, which is transported over UDP port 500. Therefore, you cannot redirect IP protocol 50 to UDP port 500, or vice versa.
Congrats, jmacmann, on getting those clients up and running! I'm gonna try that using FQDN and DDNS... sounds intriguing!
Good luck, all.