Maribel
I've reserved a lan ip for my husband and rebooted my laptop which had the offending ip address & it has now assigned me a different one - so far so good. Hubby out at present so can't see what his laptop would get when connected. However that is a lan rather than wireless so will look at Bender's suggestion of the Lynksys router too.
Bender
not sure how to add pc to dmz on my router. There is a 'default dmz server' mentioned on the wan setup page but I don't know if this is the right thing.
---------- Post added at 14:45 ---------- Previous post was at 14:24 ----------
yay

success
hubby home and connected via wireless and got the desired ip address!! momentarily I (on .4) got a message saying there was an ip conflict so I repaired the ip connection (got .4) again and hubby got his .2 and was able to connect in to work. Hope this continues to work & many thanks for your help!!