Cookie problem with iPhone?

  • Hello,
    I'm having a problem accessing an online forum via my iPhone 5s.
    I usually use the forum via my iMac, and have no problems at all.
    But if I try to enter the same username and password on the iPhone - it does not like me any more!
    It has been suggested that it may be a cookie related problem for this particular forum.
    Has anyone got any pearls of wisdom or advice with how I might deal with this situation?