I previously thought my Dad was using PPTP vpn, but have learnt today it is infact IPSEC. He has periods of connecting ok to his work vpn and periods where he can't connect at all. I checked his connection logs and every time he can't connect, he receives the same error, but ONLY on incoming connections, not the outgoing one. Incoming Connection timed out, please check your firewall isn't blocking UDP and IPSEC traffic. I am using the bundled Technicolor TG582N router with standard ADSL1. Through some research searching here and online, I have already tried the telnet command:
connection applist connection unbind application IKE saveall
I have also disabled the option on the router "disable ping from wan interface" which was causing problems with p2p connections, but it has not resolved the issue. Any pointers? The consistency of the errors remains the same whether this command is used or not.