code will be incompatible with r45 for sure;
there was a bug once that made it impossible to compile gcc5 with gcc6, not sure about the other way around
Instead of blocking the conntest page, I'd lock the url specifically used to check for browser updates
https://cbvc.cdn.nintendo.net
(example complete url for fw9.9: https://cbvc.cdn.nintendo.net/SNAKE/1/EUR)