I'm perplexed by soaring pings

[HuFlungDung]

I built a new computer with an Athlon 550, FIC Sd11 m/b, Voodoo3-3000, 128 mb pc133 ram. This machine has a USR 33.6K modem in it, (because a 56K doesn't connect above 26.4K anyway from my location, anyway). Anyway, I used to have a lot of pretty decent games of UT on my old AMD 350 system, but now I get these enormous ping spikes rising to 10000 to 15000ms. I D/L Q3 lately and I get a lot of "disconnect jack icon" while (attempting) playing. I can't help but think that there is some kind of a timing and/or communication problem within my system that may cause this. Anyone got any clues? I have used TweakDUN to optimize my Win98 internet settings. I have tried setting the UT "rate" all over the place, no change.

[Bio-Hazard]

you might try some different modem strings. do you know what your connection speed is. you can also play with netspeed in the game to see if that will help. i have those pings also. when they happen, i disconnect and get a better connection thru my server and that usually clears it up. sometimes takes 2 or 3 disconnects before i get a good one. also make sure your performance percentage is above 90% to give you all the resources possible in virtual memory.

[EASY_Target]

Put your MTU settings at minimum.

[HuFlungDung]

Thanks for your replies! I actually had my MaxMTU set at 576 (small) already. But, I just phoned my ISP to check if this was still their current recomendation ( because it was 576 a year ago), and he said they are using 1500 now. So, I'll try that for a while.
As for my modem, a 33.6K USR int fax, I found out that it is not upgradable to v.90, nor to 56K. I have other machines with 56K modems that only connect at 26.4K all the time from this location anyway, so I figured my old 33.6K would be just as good. Maybe v.34 is not that compatible with v.90? My ISP uses v.90. I have no idea of what other modem strings I could use or what I would be doing with them. Is there a list somewhere?

I did try adding a bunch of charts from the dial up adapter to my system monitor, but they didn't really show me any glitches (after playing Q3 for an hour with a typical connection that freezes for a few seconds, then goes again).

I'm seeing my ping behave the same way with UT and Q3: it looks low in the browser until I get into the game, then it jumps by about 50%, and soars skyward randomly, and settles down. I'm wondering if Q3 and UT netcode are actually more similar than everybody thinks, or else the programmers are making the same assumptions that aren't holding up.