I have sometimes had problems that were related to my isp. If i tried over my mobilephone(not connected to wifi) it worked. See if that is the issue, then you ask your isp why you cant reach a certain domain.
Would be interesting to see your logfile from epgimport, also if you only have that link in xxx.sources.xml or if you have other links. If one link does not work it just take the next one.
Enigma boxes(openpli 7.0) cant read the EPG file provided from dashboard (eg https://xxxxx.xdns.pro/epg_temp_dl/output-epgs/sweden.xml.gz) since the link is https. If it would have been http it would play nice.
Cause of that you have to find other epg links to put in...