First, a bit of background - sorry it's so long:

Ever since I got ADSL (~2 years now) it's been overall fine for whatever I've wanted to use it for.

However, recently (and I don't really know when but certainly not that long ago) I noticed that the speed of some (in fact most) secure connections were absolutely terrible.

This was mainly brought to my attention when I started trying to use Gmail with POP3 to OE. Since Google recently made their Gmail POP3 server require secure connections, it was almost impossible to use because downloads were extremely (say 0.2kB per 3 seconds - measured with netmeter) slow and there were almost always timeouts so email could effectively NEVER be downloaded to my OE.

I just kinda ignored it and used the Gmail webmail whenever I needed to use Gmail (though I hate the conversation style and the fact that you now can't turn that off)

Problem came back when Xtra upgraded to Yahoo!Xtra Pro Mail and also needed secure connections. BIG PROBLEM. Since I use my Xtra email constantly, having completely useless performance was not so good. I rang Telecom who of course just told me "It should be working" - But I was able to fix the problem by using the old (non-secured) settings. I had not been able to do this before, maybe my call to Telecom got them to change something?

Anyway they changed it back again and non-secured didn't work anymore, and I was also starting to find problems with some secured websites (HTTPS) as well.

During all this I had been trying all sorts of things, other programs, other routers, other PCs. Nothing worked. I couldn't figure it out - until I took my PC to a LAN party at a friends house and decided to check my email. It downloaded perfectly. So I thought, no matter how weird this sounds, it's got to be a problem with my actual internet connection, as I'd eliminated everything else.

So I rang Telecom again, and told them that secured connections were completely useless for me, and that as I'd tried everything else and it worked on another internet connection, it HAD to be their fault. So they did a port reset, which unfortunately did nothing, and I couldn't be bothered calling them again as it was 10PM.

Lazy people start reading here:

So the next day I googled around, posted on PressF1 and came up with the conclusion that if my MTU was set too high, packet fragmentation could occur, which apparently secure servers don't like much at all.

I lowered the MTU as low as I could (1000, down from 1500 - which is the lowest this Dynalink RTA-230 can go) and surprise! Secure email and websites worked like they should!

Now as far as I know, 1500 (or 1492) is the DEFAULT in almost all ADSL routers, WHY then does my connection have to have a significantly LOWER setting, and WHY did the default work for so long, only to cause problems NOW?